Infective juveniles of four isolates of entomopathogenic nematodes placed into balanced (mixed) salt solutions displayed varying levels of ability to osmoregulate under hyperosmotic conditions. The isolate with the greatest desiccation tolerance (Steinernema carpocapsae SCB-L1) showed the greatest osmoregulatory ability. However, the isolate with the poorest desiccation tolerance (Heterorhabditis sp. HIS-33) could also osmoregulate. One isolate with moderate desiccation tolerance (H. bacteriophora HP88) had the poorest osmoregulatory ability while another (HIS-28) showed good osmoregulatory ability. This shows that there is not necessarily a close link between hypo-osmotic regulation and desiccation tolerance. The need for separate screens for these different survival attributes is, therefore, indicated. Assessment of Heterorhabditis sp. isolate HIS-28 found that osmoregulatory ability and percent survival was greater in balanced salt solutions compared with single salt solutions, providing indirect evidence for a specific ionic regulation mechanism.