Opinions upon whether actin is present in synaptonemal complexes of eukaryotes are still controversial. We detected actin in synaptonemal complexes of spermatocytes of Mesocricetus auratus with indirect immunofluorescence technique and observed bright fluorescence in the SCs, indicating the presence of actin in the structure. We labelled sections of the spermatocytes of M. auratus with immunogold technique, gold particels were observed over the lateral elements and attachment plaques of the SCs, and many of the gold were found in clusters, confirming the results of the immunofluorescence observations. Further examinations revealed the gold particles representing actin in SCs of autosomes and sex chromosomes and also in SCs of zygotene and pachytene. Our results are in favour of the point of view that actin is a component of the SC.