OBJECTIVE: To compare the rates of and reasons for discontinuation of levonorgestrel (LNG) 52 mg intrauterine system (IUS) and LNG 13.5 mg IUS. STUDY DESIGN: In this retrospective cohort study, 81 premenopausal women aged 13-55 who underwent LNG 13.5 mg IUS insertion and 345 women who underwent LNG 52 mg IUS insertion from 1/112013 to 12/31/2015 were identified. Baseline characteristics, symptom concerns, discontinuation rates, and subsequent contraception were compared. RESULTS: Women with LNG 13.5 mg IUS were significantly younger (mean age, 25.8 vs. 30.3 years), more likely to be nulliparous (87.7% vs. 28.0%), less likely to have previously used long-acting reversible contraception (12.3% vs. 35.4%), and had lower mean body mass index (25.1 vs. 27.1 kg/m(2)). In women with contact within 24 months, 54.8% (40/73) of women with LNG 13.5 mg IUS expressed symptom concerns, as compared to 60.1% (157/261) of women with LNG 52 mg IUS (p=0.41). By 24 months the cumulative incidence of discontinuation for symptom-related concerns was 20.4% (95% CI 9.8-31.0%) and 13.9% (95% CI 9.5-18.3%) among women with LNG 13.5 mg IUS and LNG 52 mg IUS, respectively, taking into account other reasons for discontinuation. CONCLUSION: While a lower proportion of LNG 13.5 mg IUS users expressed symptom concerns, the discontinuation rate due to symptom-related concerns by 24 months was higher in this group, though not significant statistically.