Specimens of Cylicocyclus insigne (Boulenger, 1917) from Equus caballus and Cylicocyclus gyalocephaloides Ortlepp, 1938 from Equus burchelli were studied to determine whether they should be recognized as separate species. Both are relatively large species with broader than deep buccal capsules with thick, concave walls and a distinct basal external ring; a large esophageal funnel without a thick cuticular lining; and an excretory pore and cervical papillae at or near the junction of the esophagus and intestine. Although the specimens of C. gyalocephaloides are as long or longer than C. insigne, the former have a longer esophagus, males have shorter spicules and a longer gubernaculum, and females have a shorter vagina. In addition, the dorsal papillae of the genital cone of C. gyalocephaloides are more slender than those of C. insigne and bilateral spines present on the genital cones of C. insigne were not found on the available specimens of C. gyalocephaloides. It was concluded that sufficient morphological differences are present between C. insigne of E. caballus and C. gyalocephaloides of E. burchelli to recognize and distinguish both nematode species.