Seventeen patients with bladder cancer were treated with semiselective intraarterial COMPA chemotherapy. One course of COMPA consisted of 20 mg/m2 cis-diammine-dichloroplatinum (CDDP) on days 4 and 5, 0.6 mg/m2 vincristine (VCR) (Oncovin) on days 1 and 2, 5 mg/m2 methotrexate (MTX) on days 2 and 3, 5 mg/body peplomycin (PEP) on days 1, 2 and 3, and 15 mg/m2 adriamycin (ADM) on day 4. These drugs were injected every 2 or 3 weeks through a polyurethane catheter the tip of which was placed just proximal to the aortic bifurcation and during injection both thighs were tied with a pressure of over 250 mmHg. From 2 to 6 courses (mean, 4.4 courses) were administered. Of the 17 patients, 4 achieved complete remission, 10 achieved partial remission and 3 showed no change. After this COMPA chemotherapy eight patients were able to retain their bladders while seven underwent immediate radical cystectomy. The adjuvant COMPA chemotherapy for two patients with pelvic metastasis after radical cystectomy showed good results. Mild degrees of anorexia, nausea, vomiting, hair loss, numbness of fingers and/or toes, leukopenia and intestinal paralysis were observed. Instrumental troubles were seen in two cases; one involved dislocation of the tip of the catheter, the other was infection of the reservoir. Intraarterial COMPA chemotherapy is effective for neoadjuvant therapy of invasive bladder cancer, bladder-preserving treatment and adjuvant therapy of pelvic metastasis.