Human lymphotoxin (LT) was produced in E. coli as a soluble protein. The level of recombinant human LT production was about 4% of the total souble proteins of E. coli extracts. Recominant human LT was purified to apparant homogeneity by a simple procedure utilizing FPLC on Mono Q and Mono S columns. The specific activity of the purified LT was $10 imes10^7;units/mg$.