Because lymphocytic cortisol metabolism-enhanc- ing factor (LCMEF) Is absent In the plasma of cancer patients (CP), this study was undertaken to determine the Influence of tumor removal on this phenomenon. Known concentrations of human lymphocytes were incubated with cortisol in media con-taining 50% phosphate-buffered saline (PBS) and 50% of one of the following: A) homologic normal plasma (HP), b) plasma from patients with noncancerous diseases (NCD) before surgery, c) plasma from patients with NCD after surgery, d) plasma from CP before tumor removal, e) plasma from CP after tumor removal, f)plasma from long-surviving CP (LSCP), and g) PBS. With the exception of plasma from the LSCP group, all the plasma had the capacity to enhance the lymphocytic cortisol metabolism (LCM) when compared with that of PBS. There was no significant difference between the metabolism obtained with HP and that obtained with plasma from patients with NCD either before or after surgery. The plasma from CP led to a significant reduction In activity, with no significant difference in conversion rates before and after tumor removal. The plasma from LSCP failed to enhance LCM, had a conversion rate similar to that of PBS and significantly lower than that of the plasma from CP, and appeared to contain no LCMEF. These findings, which showed that the lack of LCMEF in CP is not Influenced by tumor removal, may indicate 1) that the lack of LCMEF preceded the appearance of cancer or 2) irreversibility of a possible antl-LCMEF synthesis effect waS induced by the tumor.