Background: Although radical cystectomy (RC) has been a standard treatment for muscle invasive bladder cancer (MIBC), some patients are unfit or refuse RC. Intraarterial chemotherapy combined with radiotherapy (IAC-RT) is one of the bladder preservation techniques, but there are a few data in patients who performed IAC-RT without salvage RC. The aim of this study was to evaluate the efficacy and tolerability of IAC-RT without RC compared to RC in patients with MIBC. Methods: We retrospectively reviewed patients with MIBC (T2-4N0M0) who had received either IAC-RT or RC in our hospital between January 1999 and December 2019. Intraarterial chemotherapy consisted of cisplatin (30mg/m²) and adriamycin (20mg/m²) on day 1 of each 1st, 2nd, 5th, 6th week. Concomitant radiotherapy (2 Gy/session, total 60 Gy) to whole pelvis was performed during chemotherapy. Salvage RC was not performed in all patients. Overall survival (OS), disease-specific survival (DSS), and metastasis-free survival (MFS) were compared between patients who received IAC-RT and RC. The prognostic factors of IAC-RT associated with OS were also investigated. Results: Forty-two and 143 patients received IAC-RT and RC, respectively. Of 42 patients who received IAC-RT, 28 (67%) and 14 (33%) were elective (refused RC) and imperative (comorbidity:7 poor PS:6 unresectable:1) cases, respectively. The patients who underwent IAC-RT were older (median; 77 vs 69 years old) and had poorer PS (≥2; 43% vs 4.9%) and shorter follow-up time (median; 21.9 vs 40.0 months) than those of RC. During follow up periods, metastasis, bladder cancer death, death of any cause was observed in 20, 19, and 27 patients with IAC-RT, 59, 55, and 49 patients with RC. In survival analyses, median OS was 38.7 months (95%CI, 16.9-74.7) with IAC-RT versus 154.0 months (95%CI, 70.6- not estimable (NE)) with RC, these OS curves were significantly different (P=0.001). There were not significant differences between two groups in DSS (median 46.5 vs not reached, P=0.06) and MFS (median 38.7 vs not reached, P=0.21). In multivariate analysis, clinical stage (≥T3; HR, 1.89; 95% CI, 1.04-3.46; P=0.04) and PS (≥2; HR, 2.24; 95% CI, 1.16-4.33; P=0.02) were suggested as risk factors associated with poor OS, however, treatment procedure (IAC-RT or RC) did not associate with OS. Forty of 42 (95%) patients with IAC-RT had any adverse events (AEs). Although grade3 AEs were observed in 21 (50%) patients, most of them were hematological AEs and Grade 4/5 AEs was not observed. Conclusions: IAC-RT was a useful and tolerable treatment option for patients with MIBC who were unfit or refused RC.