Purpose To evaluate the effectiveness of catheter-directed sclerotherapy (CDS) with 95% ethanol in patients with primary or recurrent ovarian endometriomas. Materials and Methods In this prospective study, 14 participants (mean age, 32 years; range, 20-44 years) who underwent CDS for ovarian endometrioma from March 2015 to December 2017 were evaluated. Diagnosis was based on symptoms and imaging studies. To assess the impact of CDS on ovarian reserve, serum anti-Müllerian hormone (AMH) was measured before CDS and 6 months after CDS. Serum cancer antigen 125 (CA-125) levels were also measured at the same time points. Follow-up US was performed 1, 3, and 6 months after CDS and biannually thereafter to monitor potential cyst size change and recurrence. Comparison of AMH, CA-125, and cyst size before and after CDS was performed by using the paired t test or Wilcoxon signed-rank test. Results Mean endometrioma size decreased from 5.8 cm ± 2.2 to 1.1 cm ± 1 (P ˂ .001). During a mean follow-up of 12.7 months (range, 6.1-23.0 months), there were no recurrences of endometrioma. Pain was relieved in all participants, with a decrease in serum CA-125 level (P = .001). There was no difference in serum AMH level before and 6 months after CDS, indicating well-preserved ovarian function (4.29 ng/mL ± 2.47 vs 4.36 ng/mL ± 1.94, respectively; P > .875). There were no procedure-related complications. Conclusion Catheter-based sclerotherapy with 95% ethanol can lead to better short-term clinical outcomes and well-preserved ovarian function for patients with endometriomas.