A simple technique for inducing the production of peritoneal exudate cells within 3 to 4 days in chickens is described. In each 5 to 6 week old chicken, 5 to 8 ml of washed Sephadex particles suspension in saline (3%) were injected intraperitoneally. Three to 4 days later, peritoneal exudate cells were harvested, washed, suspended in Hank's solution, counted and adjusted to one million cells per ml. In each well of 4-chamber slide 1 ml of peritoneal cell suspension was incubated at 37 degrees C for 30 min. Cultures were then gently washed several times leaving a monolayer of glass adherent cells. The phagocytic activity of these adherent cells was examined using either latex particles or antibody-sensitized sheep erythrocytes. The monolayer cells were incubated with particles in Hank's solution (with excess particles in particle/peritoneal cell ratio) for 1 h at 37 degrees C. From 99.5 to 100% of the monolayer cells were found actively phagocytic for either the latex particles or sensitized erythrocytes or both. Adherent cell monolayers were cultivated in vitro for several weeks with no detectable decrease in their phagocytic activity.