The earthworm somatic muscle contains myoneural synapses forming clusters of «synaptic buttons» which were identified by the help of fluorescent dyes FM1-42, FM2-10, FM4-64. In synaptic buttons proteins syntaxin 1, synaptotagmin 1, and alpha 1В subunit of the Ca2+-channel of the N-type were identified. It is supposed that «synaptic buttons» contain a limited number of active zones, which is due to their small size (1--2 mkm) and the pattern of distribution of proteins of the exo-endocytotic cycle. The postsynaptic membrane of cholinergic synapses contains nicotinic acetylcholine receptors able to bind alpha-bungarotoxin. At the end plate zone miniature excitatory postsynaptic currents were registrated. The area of location of receptors on postsynaptic membrane is strongly restricted with the synaptic contact region.