To investigate the efficacy of 24-h interval multiple-session ethanol sclerotherapy for the treatment of simple renal cysts. The study sample included 58 patients (mean age, 65.37 ± 11.95 years). We included 76 simple renal cysts that were treated with percutaneous aspiration with a minimum of two sessions of 95% ethanol sclerotherapy in a 24-h interval between sessions. Patients were evaluated at 1, 3, and 6 months after the intervention for the efficacy of the treatment. Treatment success was defined as a complete regression of a cyst or a > 50% reduction in its volume, with no recurrence of symptoms. The mean preprocedural cyst size was 72.98 ± 25.14 mm, and the mean preprocedural cyst volume was 205.76 ± 244.15 mL. The mean volume of ethanol used in the first sclerotherapy session was 62.76 ± 30.71 mL. The mean fluid accumulation in the cysts at the end of the first 24-h interval was 4.66 ± 7.13 mL. The mean quantity of ethanol used in the second sclerotherapy session was 26.48 ± 22.2 mL. A third sclerotherapy session was required in only 10 (13.2%) of the cysts. The mean follow-up period was 52.84 ± 37.83 months. The rate of complete regression was 97.4% for the whole sample at the end of the follow-up. Ethanol ablation with 24-h intervals is a safe and effective treatment option in the minimally invasive percutaneous treatment of simple renal cysts.