The leopard gecko, Eublepharis macularius, has temperature-dependent sex determination (TSD). Previous reports have shown that females are produced predominately at cool incubation temperatures and males are produced predominately at warm incubation temperatures (Pattern Ib). We report here that incubation at even higher temperatures (34 and 35°C) produces mostly females (Pattern II). The lethal maximum constant incubation temperature for this species appears to be just above 35°C. Although a previous study indicated that females from a warm incubation temperature (32°C) failed to lay eggs, we found that 12 of 14 mature females incubated at 32.5°C, and 5 of 6 mature females incubated at 34°C produced fertile eggs and viable hatchlings. © 1993 Wiley-Liss, Inc.