Effects of relative humidity on reproductive behavior of smokybrown cockroaches,Periplaneta fuliginosa(Serville), were studied. Groups of five field-collected females (newly molted and mated) were placed in aquaria containing four substrate choices for oviposition (peat, marble chips, a simulated wall void, or bare floor). Aquaria were maintained in humidity chambers set at either 50–55, 65–70, or 80–85% RH. After 49 d, adults were removed from the aquaria and location and number of oothecae were recorded. Oothecae were kept separately until nymphs were counted after eclosing. Peat was the substrate used most often for oviposition. Variations in humidity did not have a significant effect on substrate choice, numbers of oothecae produced, or eclosion rate of oothecae. Oothecae that were glued to a substrate had a significantly greater eclosion rate than those that were not glued. It is not known whether a female can detect which oothecae are viable and subsequently invests the time and energy to glue them to a substrate or whether gluing oothecae enhances their eclosion rate.