The studies investigating antitumor efficacy of bacterial infections, started by Coley, resulted in isolation of tumor necrosis factor (TNF-alpha), released by activated macrophages. It was hoped that direct and indirect cytotoxic, cytostatic and immunomodulatory effects of TNF-alpha would prove helpful in obtaining an effective antitumor drug. In this paper, we describe biologic and immunologic activity of cachectin as well as pre-clinical trials of TNF application in antitumor therapy.