There are many reports describing the receptorial distribution in animal eyes but only a few reports concerned with human eyes. Because of this, we have studied five fresh human eyes, in vitro, by a very sensitive method. We have proved the existence of alpha exciting and beta 2 relaxing receptors on the iridial dilatator muscle and the absence of cholinergic, serotoninergic, dopaminergic, histaminergic receptors. On the contrary, on the circular muscle we have found muscarin cholinergic receptors without adrenergic ones.