In this paper, the effect of tritoqualine (TRQ) on the proliferation of interleukin (IL) sensitive cells was investigated. TRQ inhibited the proliferation of FDCp-2 (IL-3 dependent cell line), CTLL-2 (IL-2 dependent cell line) and bone marrow cells (BMC) stimulated by IL, giving an ID50 of about 3 microM equally in the three systems. However, a ten times higher concentration of TRQ was required to inhibit the tumor cell proliferation. TRQ did not affect the unstimulated bone marrow cells. Accordingly, it is suggested that TRQ may show its anti-allergic effect, at least partially, by interfering with the proliferation/differentiation to mast cell and basophils of multi-functional hemato-poietic cells stimulated by IL-3.