In this study, the effect of nest temperature and surrounding sand temperature on sexual differentiation were examined for green turtle (Chelonia mydas) hatchlings on Sugözü Beaches (Adana, Turkey) in 2005 nesting season. Nest temperatures were found to be higher than the surrounding sand temperatures, especially du- ring the middle and last third period of incubation (respectively, 0.6°C and 1.9°C). The nest temperature was mostly related to the incubation duration and this was followed by the distance of the nest from the sea and the clutch size. Any relationship between nest temperature and nest depth was not found. Nest temperatures (ranged between 29.4-31.6°C) and middle third temperatures (ranged between 29.5-31.3°C) were measured above 28.9°C, which is the pivotal temperature. The sex ratio in green turtle hatchlings in the area investigated according to the temperature profile was prominently biased toward females.