OBJECTIVE To evaluate the efficacy of clarithromycin (CAM) treatment in adult Chinese patients suffering from chronic rhinosinusitis with nasal polyps (CRSwNP) or without nasal polyps (CRSsNP). METHODS A prospective, open and self-controlled clinical trial on patients with CRS was conducted. Fifty patients met inclusion criteria. Of 50 patients, there were 33 patients with CRSsNP and 17 patients with CRSwNP. CAM was administered at 250 mg/d and the duration of administration was 12 weeks. Outcome measures included assessments of visual analogue scale (VAS), the sino-nasal outcome test-20(SNOT-20), the medical outcomes study short-form 36 items(SF-36), Lund-Kennedy endoscopy score, and Lund-Mackay computed tomography score. Before starting the treatment, 2 months after treatment and at the end of treatment, each patient had to complete all the measures except Lund-Mackay computed tomography score, which was only conducted before and after treatment. In order to evaluate the safety of CAM, liver function and renal function in all patients were detected before and after treatment. SPSS 16.0 software was used to analyze the data. RESULTS Forty-five patients completed 3 months follow-up and 5 patients withdrew due to different reasons. The results were as follows: (1) Thirty-three patients with CRSsNP's VAS scores of four time point were 5.81 ± 1.69, 3.76 ± 1.94, 2.98 ± 1.95, 2.06 ± 2.13, respectively, there were statistically significant improvements in turn (t values were 5.910, 8.090, 8.932, all P < 0.05). Endoscopy score of four time point were 6.28 ± 1.28, 5.00 ± 1.67, 4.12 ± 1.76, 3.12 ± 2.19, respectively, there were statistically significant improvements in turn compared with before treatment (t values were 6.662, 9.161, 9.936, all P < 0.05). The CT scores before and after treatment were 10.33 ± 4.65 and 4.67 ± 4.59, respectively (t = 7.226, P = 0.000) . (2) Seventeen patients with CRSwNP's VAS scores of four time point were 6.07 ± 2.02, 4.87 ± 2.61, 4.06 ± 2.85, 4.08 ± 2.80, respectively, there were statistically significant improvements after 2 or 3 months (t values were 3.285, 3.468, both P < 0.05) except after one month (t = 1.846, P > 0.05). Endoscopy score of four time point were 10.65 ± 1.77, 9.35 ± 1.93, 8.65 ± 2.76, 8.47 ± 2.76, respectively, there were statistically significant improvements in turn(t values were 4.068, 4.863, 5.156, all P < 0.05). The CT scores before and after treatment were 13.82 ± 4.94 and 11.41 ± 5.12, respectively (t = 3.975, P = 0.001). (3) During the period of CAM treatment, 1 patient reported a tolerable headache and weakness and 1 patient had abdominal pain after two months treatment, all the symptoms disappeared while they were asked to stop the drug. Liver function and renal function were detected in 40 patients, the differences before and after treatment were not significant statistically. CONCLUSIONS Long-term, low-dose CAM treatment is effective in the treatment of CRSsNP and CRSwNP in Chinese patients. Meanwhile, the efficacy of CAM is more significant in polyp-free group compared with polyp group. Low does CAM therapy is safe, and the liver function and renal function does not worsen after 3 months treatment.