The objective of this work was to devise an in vitro system for studies on cytokine secretion by synovial membrane treated as a whole organ with various synoviocyte populations. Synovial membrane from knee joints of WAG rats was dissected and incubated in culture medium without serum for 4 - 48 h. The level of IL-1alpha was determined in synovial lysates and IL-6 in culture medium. The synovial membrane from left and right knee joint of the same rat produced similar amount of cytokines both in lysates and in the medium. Synovial membrane stimulated by LPS for 4 or 24 h gave significantly stronger cytokine response than the membrane from the opposite (control) knee. After 48 h incubation of synovial membrane drastic drop in cytokine level was noted, which indicated on deterioration of the membranes. The test may be useful in studies on factors affecting cytokine secretion by synoviocytes.