Ascitic fluid and peripheral blood samples, from seven patients affected by peritoneal carcinomatosis secondary to ovarian tumors, were analyzed to examine the phenotypic properties of ascitic fluid-associated lymphocytes (AFAL) and then asses T-cell activities in the presence of different interleukins. The AFALs showed a relative enrichment of CD2+, CD3+, CD5+, CD4+ T cells compared to the peripheral blood samples, while the contrary was true for CD56+ and CD57+ cells. The same phenomenon was observed in both CD3+, CD56+ and CD2+, CD56+ cell populations. Fewer CD71+ and CD25+ cells were found in the ascitic fluid suspensions whilst the opposite was true for HLA-DR+ lymphocytes. The data obtained from the in vitro incubation of AFALs in the presence of IL-1 (or), IL-2, IL-4, IL-6 or IFN showed that IL-1, IL-2 and IFN- can induce a two-fold increase in the percentages of HLA-DR+ T lymphocytes. IL-6, IL-2 and IL-1 seemed to have a fairly modest effect on CD25. A better survival of CD56+ cells was found only in the presence of IL-4 and IL-6. Even though preliminary and based on a limited number of patients, our results would seem to invite caution in instituting intraperitoneal administration of one or more cytokines for the treatment of such lesions in humans.