PURPOSE: While seasonal variation of stone disease is well described, the time to formation of urinary calculi is unknown. Because southwestern Asia is a high risk environment for stone disease, the date of entry into this region is a definitive beginning to a period of increased risk of urinary calculi. The recent influx of Department of Defense personnel into southwestern Asia provided the opportunity to observe stone disease in a cohort of healthy personnel during a well-defined period of increased risk of stone formation. MATERIALS AND METHODS: A database was constructed for all patients presenting with symptomatic urinary calculi to a single military hospital deployed to Kuwait from March through August 2003. Patient demographics, stone characteristics and time to formation of symptomatic urinary calculi were evaluated. RESULTS: A total of 182 patients were diagnosed with 218 symptomatic stones. Mean time to formation of symptomatic urinary calculi was 93 days with a standard deviation of 42 days. CONCLUSIONS: This study provides unprecedented information about the development of symptomatic urinary calculi in a high risk environment. While unique aspects of the population, environment and medical system created a singular opportunity to study stone disease, the results of this study are applicable to the general population.