Three domestic cockroach species, the American cockroach, Periplaneta americana; the Smoky brown cockroach, Periplaneta fuliginosa; and the German cockroach, Blattella germanica were used in this experiment to determine the effect of mating on oviposition and possibility of parthenogenesis. In comparison with mated females, unmated females of P. americana and P. fuliginosa had a longer adult lifespan, but produced obviously fewer oothecae, including many malformed oothecae. The malformed ootheca rate was higher than 60%. However, unmated females of B. germanica were similar to mated females in adult lifespan and the oviposition cycle, and all the oothecae produced by unmated females were normally formed. Parthenogenesis was found in P. americana and P. fuliginosa. The hatchability of oothecae produced by unmated females, which the malformed oothecae were not counted, was 18.7% in P. americana, and 16.7% in P. fuliginosa. All the parthenogenetic progeny were females. Parthenogenesis was not found in B. germanica, oothecae deposited by unmated females were desiccated and fell of before new oothecae were produced.