Growth and survival of Penaeus semisulcatus larvae were measured in factorial combinations of temperature (20°, 23°, 26°, 29°, and 32°C) and salinity (28‰, 29‰, 32‰, 34‰, and 37‰). Three experiments were maintained for 5 to 6 d, between late nauplius and first mysis stages. Salinity did not have a significant effect on growth or survival above 28‰. At 28‰, both growth rate and survival decreased (although the reduced survival occurred only at the lowest temperatures). While temperature had a substantial and regular influence on growth rate (larvae growing more rapidly at warmer temperatures), the effect on survival was not clear. In one experiment, there was significantly lower survival at the higher temperatures (32° and 29°C); however, temperature did not affect larval survival at all in the other two experiments. The results were compared with six years of published data on temperatures and salinities in Albatross Bay, Gulf of Carpentaria, Australia, and indicate that naturally occurring salinities are unlikely to directly affect survival of P. semisulcatus larvae in that area. Summer temperatures regularly exceed 29°C, raising the possibility (from the results of one experiment of three) that high temperatures may cause larval mortality in Albatross Bay. However, other published evidence indicates that such an effect is unlikely to have practical significance.