Peplomycin emulsified in hydroxypropyl cellulosum (HPC-PEP) was prepared for intravesical chemotherapy. Clinical efficacy of HPC-PEP and tissue concentration of peplomycin (PEP) were studied in 12 patients with bladder tumor. Histopathology showed transitional cell carcinoma; 2 in grade 1,8 in grade 2, and 2 in grade 3. The total volume of 30 ml HPC-PEP was prepared from a mixture of 2% HPC and 90 mg PEP in 15 ml saline, and was intravesically administered through a urethral catheter and retained for two hours. Clinical evaluation 7 days after the initial instillation demonstrated good tumor regression in 2, good response in 5, and no change in 5. The mean PEP level in tumor tissue was 0.36 microgram/gr after 7 days and 0.19 microgram/gr even after 14 days. These clinical observations and tissue levels of PEP suggest that HPC-PEP might be useful as an intravesical instillation agent for bladder tumor.