Abstract: We studied the ultrastructure of epididymal spermatozoa of Eumeces elegans.After epididymal tissues of E.elegans were double fixed with 2.5% glutaric dialdehyde and 1% osmic acid,the ultrathin section were observed under H-600 transmission electron microscopy.The spermatozoa contain two major components,a head and a tail.The head contains an acrosomal complex and a nucleus,and the tail a neck,a midpiece,a principal piece and an endpiece.The mature spermatozoa are characterized by:a depressed acrosome at the anterior portion;an acrosomal vescile divided into cortex and medulla;a subacrosomal cone filled with paracrystalline subacrosomal material;a pointed prenuclear perforatorium;a stopper-like perforatorium base plate;an elongated nucleus;an epinuclear lucent zone;rounded nuclear shoulders;a coned nuclear fossa;a bilateral stratified laminar structure within neck region;absence of a endonuclear canal;a long axis of the proximal centriole almost vertical to that of the distal centriole;nine peripheral dense fibres connecting inward with the corresponding 9 triplets of the distal centriole,and backward with the doublets of the axoneme;central fibres connecting with the two central singlets;a short midpiece;columnar mitochondria with linear cristae;each intermitochondrial ring structure consisting of the complete ring of small regularly ovoid or small trapezoid dense bodies;a fibrous sheath into the midpiece;an annulus closely attached to the inner surface of the plasma membrane;the arrangement pattern of the ring structure and mitochondria in rs1/mi1,rs2/mi2,rs3/mi3,and rs4/mi4;mitochondria in order of 10 in transverse section;a thin zone of cytoplasm at the anterior portion of the principal piece;the enlarged fiber 3 and fiber 8 disappearing at the anterior portion of the principal piece;the axoneme complex having an usual 9+2 pattern.The sperm ultrastructure of E.elegans is similar to that of the species within the Sphenomorphus and the Egernia groups,but evidence of spermatozoal autapomorphies is not found in E.elegans.