Feeding activities of the predatory nematodes Laimydorus baldus and Discolaimus major were studied under laboratory conditions in relation to temperature (5–40°C), prey density (25–250 individuals), predator starvation (0–12 days) and prey incubation (4–24 h) using the rice root nematode, Hirschmanniella oryzae, as prey. Prey search duration, rate of predation, and the number and duration of predators feeding and aggregating at feeding sites were studied. Discolaimus major killed more prey, and fed and aggregated longer than L. baldus. Predator activities at the feeding site were optimal at 30°C. Predators starved for 6 days required the briefest prey search duration, and remained aggregated at the feeding site for a longer duration. Predators were increasingly efficient at search prey as prey density increased. Prey search and feeding durations were shortest when prey nematodes were incubated between 8–16 h. Predation rate was optimal when prey were incubated for 16 h. Prey search and killing abilities of L. baldus and D. major were governed by temperature, prey density, starvation and prey incubation, and depended upon feeding duration, number of predators feeding and aggregating at the feeding sites.