Biologic therapies are playing an increasingly important role in the treatment of patients with cancer. A better understanding of immune responses to tumors now exists, and more defined reagents are now available including new recombinant cytokines, cultured lymphoid cells of defined specificity, and most recently, vectors containing specific genes that can be introduced either into tumor cells or lymphoid effectors. During this past year, we have observed the reporting of new cytokines identified and tested in humans and the advent of cytokine gene therapy. The successful application of these new reagents either singly or in combination will require significant ingenuity, resources, and intuition over the next decade.