This study was undertaken to determine the combined effects of temperature and salinity on the incubation time and hatching rate of Penaeus semisulcatus eggs in controlled laboratory conditions. Fertilized eggs, from a female caught in nature and spawned in our laboratory, were stocked in 2-1 round bottom glass flasks and received one of nine temperature (24, 28 and 32degreesC) and salinity (30, 35 and 40 ppt) combinations. The eggs hatched in all treatments. The hatching rate increased as salinity increased and was highest at 24degreesC. In terms of hatching rate, the best combinations in descending order were 24degreesC at 40 ppt, 32degreesC at 40 ppt and 28degreesC at 40 ppt. However, the incubation time was longer at 24degreesC (17.5 h) than at 28degreesC (14.5 h) or 32degreesC (11.5 h).