Ceftizoxime (CZX) and latamoxef (LMOX), new synthetic cephems, are stable against various types of beta-lactamase and highly active against Gram-negative rods, such as H. influenzae, Serratia, Enterobacter and indole (+) Proteus. In this study, we evaluated clinical effects of CZX and LMOX in the clinical management of infections in acute leukemia. Sixteen episodes of infections were treated with CZX or LMOX. Four causative organisms, P. aeruginosa, S. faecalis, K. pneumoniae and A. faecalis, were identified in 2 episodes of infections. Clinical effects were recognized at 75% in 8 episodes treated with CZX and at 71% in 7 episodes treated with LMOX, respectively. The transient evaluation of GOT, GPT and Al-P, recognized in several cases. In conclusion, the clinical effects of CZX and LMOX are promised in clinical management of infections in acute leukemia.