Probstmayria gombensisFile, 1976 (Nematoda: Cosmocercoidea: Atractidae) individuals discharged in the feces of eastern chimpanzees, Pan troglodytes schweinfurthii, in Bulindi, Uganda, were examined morphologically. Adults and fourth-stage larvae, all females, found in the feces, and the third-stage larvae excised from the uterus of the gravid females were described. By close observation of the molting worms, it was considered that the uterine third-stage larvae attain molting phase, and then are laid to become fourth-stage larvae. Nutrients required for larval development in the uterus seem to be supplied by the mother after the eggshell is formed. After some growth in the host intestine, the fourth-stage larvae undergo the final molt to the adult stage. The genital primordium was very small in the early fourth-stage larvae but rapidly developed with embryonation in the pre-molt and molting phases. Such precocity suggests parthenogenetic reproduction without insemination by males. This style may enhance rapid autoinfection in the host intestine under the condition of male worm scarcity. Several ellipsoidal pseudocoelomocytes with granules of unknown function were found ventral to the intestine of the adults, fourth-stage larvae, and third-stage larvae.