Patrice Thibaud and Phillippe Leygnac don't mess about - well they do, on stage, but in the Fringe flyer advertising their show they dive straight in, no pussy-footing, no smarmy little niceties. Just a sleeves-rolled-up statement: "A funny Frenchman? Yeah right. A funny French mime? Don't make me laugh."

The rest of the promotional spiel goes on to say that, yes, you will laugh because ... now I could, at this point, pour myself another coffee and muse on the nature of comedy. Does humour, even wordless clowning, travel well? Did the influence of the late Marcel Marceau produce such a surfeit of white-faced folk in stripey jumpers, encountering invisible walls, that the words French and mime in the same sentence are, for many Fringe-goers, no joke?

But as images of Thibaud and Leygnac start springing to mind - not just making me smile, but actually laugh out loud again - I'll cut to the chase. Their show is called Cocorico (*****) and it is a hoot, a treat, a revelation and a tonic. Leygnac, small and dapper, is the pianist-cum-deadpan foil to the larger, genially exuberant Thibaud. It's their volatile relationship - with its shows of disdain, animosity and petty little one-upmanship games morphing into full-blown confrontations - that transforms a series of astutely observed, skilfully charactered situations into much more than a genuinely funny mime show.

There's a moment when Thibaud, with the sinuous agility of a determined cat, wants to get Leygnac's attention. Maybe it's boredom. Maybe it's a bid for affection. There's a whole underlying motif of the supposedly controlling Thibaud craving mutual connection and camaraderie, but as he clambers over the piano, failing to distract Leygnac from his playing, the comedy is bitter-sweet with insights into human nature, emotional needs and inter-dependency.

Wit, invention, style and virtuousity: Cocorico has all these trump cards - but it also has something more elusive. It has real artistry and a poetic sensibility that understands why we need laughter. Merci bien, messieurs.

Le Navet Bete sound as if they're a French company. They're fooling. And Zemblanity (****) merrily proves just how good this bunch of English zanies are at the business of codding, kidding and clowning around. There could be a plot, hovering somewhere in the wings. But what with all the outbursts of acrobatic tumbling, the daft gallumphing dances and oddball songs - to say nothing of the unicycling that comes and goes, and why not? - we're not at all bothered that there's really very little reason for bowler-hatted Hans (Nick Bunt) and his accent to go travelling.

"Not funny!" he says, reproachfully, as we all crack up at yet another mishap or goofy manifestation from the other talents in the group. But of course it is funny. And the sheer honed precision of what these guys do, the spot-on timing and the larky incongruities, ensure that the ridiculous absurdity of Zemblanity doesn't miss a trick.

Circa (****) is happy for audiences to laugh at some of the antics in this sampler showcase of extracts from various full-length productions. But, actually, what this Australian company majors in is the kind of imaginative new circus where high-octane acrobatic skills are choreographed into more than just a gasp-inducing spectacle.

You will, nonetheless, gasp at the prowess that sees bodies flick-flack at speed across the stage or balance atop each other in combinations that look like oriental calligraphy, with only one leg or one arm supporting the pillar of elegantly arranged limbs. You might even wince at the sight of a woman in very high stiletto heels using those heels like scarlet talons, or crampons, to scale the torso of an unflinching male partner. But you'll applaud the balances they create, not least because those shoes make you focus on the effort, the skill and indeed the probable pain that attaches to these acts.

Circa is at once sophisticated and lo-tech in its outlook. Even the hoops that set up challenges for sure-shot flying acrobats are themselves human. It's a recurring emphasis here: flesh and blood aspiration, endeavour, co-operation, ingenuity - it's what took man to the moon, so why not bathe your stunning performers in a starry spangle of lights? Just one of Circa's crowd-pleasing moments.

Laughter's a funny thing. Just think of the nervous giggles that trickle out when audiences aren't sure they like - or are embarrassed by - what's happening on stage. Me Too (***) runs that risk, with Ulrike Quade's puppet show about Siamese twins who perform in a sleazy cabaret show. With an uncannily effective rubber head sprouting from her shoulder - three "breasts" and bare buttocks incorporated into her teensy showgirl costume - Quade quite brilliantly brings Daisy and Violet to life. And doesn't shy away from the graphic, titillating nature of the freaky sideshow aspect of their existence - using coloured vibrators to represent an audience of prurient punters is slyly clever - but really her performance is about the twins' inner tensions, the conflicts of a shared identity and the yearning to be physically and mentally alone, even if separate survival isn't ever going to be possible.

It's not an especially comfortable show, once you start looking beyond the flirty come-ons that Quade invests with sauce and humour. And it's not a puppet show for kids (over 16s only) but it is a tour de force of manipulative invention - and the creepy baby is the stuff of nightmares, enough to make you wary of foam rubber for life.

Maybe it was a flat night for Fiat Lux in Strike (**). But this instance of French mime - seven characters, from different nationalities, share a long wait for a train - could hardly raise a laugh. The situations seemed weary with cliche and the strand about the Muslim couple (he is tyrannical about her wearing a headscarf, she is rebelling and the other travellers view them with a mix of suspicion and hostility) touched nerves that are perhaps too raw for any laughter to be a reconciling balm.

Cocorico, Me Too and Strike are at New Town Theatre until August 30 (not 17). Strike alternates with Nouvelles Follies.

Zemblanity is at Bedlam Theatre until August 29.

Circa is at Assembly @ Assembly Hall until August 31 (not 17 or 24).