Abstract 1. 1.Effects of habitat on the thermal regime were investigated in two diurno—nocturnal geckos in Hawaii. 2. 2.In trees Hemidactylus frenatus thermoregulated in daytime with body temperature (BT) above air temperture (AT); in houses some thermoregulated likewise in daytime but mainly the species thermoregulated at night, on electric lamps, to the same BT as in trees by day. 3. 3. Lepidodactylus lugubris in trees thermoregulated in daytime, its BT lower than in H. frenatus. In the rocks it had at night a BT resembling that in trees in daytime, because the thermal cycle in rock crevices lagged behind outside AT. 4. 4.The flexibility of these geckos in thermal regime and activity cycle preadapts them to both migration and invasion of houses.