A phase I clinical and pharmacokinetic study of recombinant human tumor necrosis factor (rH-TNF) was conducted in a single dose schedule in 33 patients with advanced cancer. rH-TNF was given by i.v. infusion over 30 min with a starting dose of 1 x 10(5) units/m2. The dose was escalated up to 16 x 10(5) units/m2 according to the modified Fibonacci scheme. Toxic effects were similar but not identical to those reported with interferons and interleukin-2, and included fever, rigors, nausea and vomiting and anorexia in a non-dose-dependent manner, and hypotension, leukocytosis, thrombocytopenia and transient elevation of transaminases (SGOT and SGPT) in an approximately dose-dependent manner. DIC syndrome was observed in one patient who had received 16 x 10(5) units/m2. The dose-limiting toxicities were hypotension, thrombocytopenia and hepatotoxicity, and the maximum tolerated dose in a single i.v. infusion of rH-TNF appeared to be 12 x 10(5) units/m2 when thrombocytopenia and elevation of SGOT and SGPT were taken as the dose-limiting toxicities. However, if hypotension was included, the maximum safely tolerated dose appeared to be 5 x 10(5) units/m2.