Objective: The aim of the study is to determine the effectiveness of extracorporeal shock wave lithotripsy (ESWL) therapy for isolated lower caliceal calculi. Patients and Methods: We analyzed 165 patients who were treated with the Siemens Lithostar Plus on an outpatient basis between March 1993 and August 1997. The age of patients ranged from 17 to 70 (mean 39.11) years. The stone size varied from 4 to 42 mm, and patients who had stones larger than 21 mm had a double-J stent inserted prior to treatment. Results: The overall stone-free rate at 3 months was 53.33%; whereas it was 61.79, 48.27, and 27.27% according to the stone size, less than or equal to 10, 11-20 and greater than or equal to 21 mm, respectively. Complications were rare, including 2 pyelonephritis, 2 subcapsular hematoma formation, 24 renal colics and 8 stone streets, which were managed by ureteral stenting or additional ESWL and resulted in complete stone clearance. Conclusion: ESWL therapy is a reasonable and effective method for small lower caliceal stones, but due to its relatively low stone-free and high complication rates, percutaneous nephrolithotripsy or open surgery should be considered for stones larger than 21 mm.