Objective To evaluate the efficacy and safety of sclerotherapy as the treatment of infected postoperative lymphocele in gynecologic malignancy patients. Materials and methods Percutaneous catheter drainage (PCD) with or without sclerotherapy was performed for postoperative lymphocele in 75 patients from 2002 to 2014. Eighty-eight lymphoceles (43 non-infected as group A, 45 infected as group B) in 75 patients (mean age ± SD; 50.3 ± 11.3) were included. Sclerotherapy was performed in 17 (39.5%, group A-S) lymphoceles in group A and 14 (31.1%, group B-S) in group B. Absolute ethanol was the most frequently used sclerosant (28 of total 36 sessions). Mean follow-up period was 37 months (range: 1–154). Results Sclerotherapy was clinically successful in 13 lymphoceles in both group A-S (76.5%) and group B-S (92.9%) without statistical significance. Compared to the pre-sclerotherapy period, group B-S demonstrated significantly decreased drainage volume after sclerotherapy (662.7 ml vs. 100.6 ml, p = 0.019). Group A-S failed to demonstrate significant decrease in drainage volume after sclerotherapy. Recurrence occurred in 4 patients in group A-S and 1 in group B-S, without statistical significance. No major complication was noted. Conclusion Sclerotherapy significantly reduces the drainage volume, and might help shorten catheter placement time in infected lymphoceles.