【Abstract】 Objective Catheter infections including exit-site and tunnel infections can result in peritoneal dialysis-related infections, leading to catheterization failure. Recently, the Exit-Site Score (ESS) has been used in children to diagnose the infection at the exit site. ESS may be more convenient and practical than microbiological methods. The objective of this study was to evaluate the effect of mupirocin on ESS in continuous ambulatory peritoneal dialysis (CAPD) patients. Methods We used cross-section method to study 80 CAPD patients treated in this dialysis center. ESS was judged by 5 clinical presentations: erythema (none, 0; ＜0.5cm, 1; ＞0.5cm, 2), crust (none, 0; ＜0.5cm, 1; ＞0.5cm, 2), tenderness (none, 0; moderate, 1; severe, 2), swelling (none, 0; moderate, 1; severe, 2), and discharge (none, 0; clear, 1; purulent, 2). ESS score 4 or greater was considered as having exit-site infection, and that of less than 4 may or may not have infection. We chose 21 patients with ESS score 2 or 3, and randomly assigned them into treatment group (n = 10) or control group (n = 11). For treatment group, mupirocin was applied on the exit of peritoneal catheter everyday. For control group, only routine clean procedure was used. ESS was judged again after one month. Results ① In the 80 peritoneal dialysis patients, ESS score 4 or more than 4 were found in 3 cases (3%), ESS scores 2-3 were found in 21 cases (26%) with the average score of 2.7±0.6, and ESS score 0 was found in 40 cases (50%). ② In the treatment group, the average ESS score decreased from 2.7±0.6 to 2.2±0.5 (P＜0.05) after the treatment for one month. In control group, however, ESS score had no significant change after one month. ③ In diabetic patients on peritoneal dialysis with the distance less than 1.5cm between superficial cuff and skin, ESS score was usually greater than that in non-diabetic patients, and their ESS score decreased significantly (P＜0.05) after local application of mupirocin. Conclusion ① Local application of mupirocin on the tube exit site was useful for the improvement of ESS score in patients with ESS score 2-3. ② More studies are needed to elucidate whether this treatment can lower the peritonitis incidence in CAPD patients and to find out the treatment for the patient with refractory infection at the exit site.