Urolithiasis in sows and neonatal pigs is well-known, but information on its occurrence and impact in finishing pigs is sparse. This study reports three outbreaks of urolithiasis in finishing pigs. In one herd, no symptoms were observed, whereas in the other herds the presence of calculi caused obstruction of the urinary tract resulting in death. Using infra-red spectroscopy, the predominant mineral-type found in the uroliths was calcium carbonate (calcite). Only small amounts of calcium oxalate (<1%) could be detected. A high urinary pH, small abnormalities in the mineral composition of the feed and insufficient drinking water were the most important risk factors identified. To prevent urolithiasis, it is important to ensure adequate water intake, to provide a balanced mineral diet, and to avoid urinary tract infections.