RESUMEN. - En Uruguay la urolitiasis en bovinos ha sido descrita en sistemas de engorde a corral. El presente trabajo describe un brote de urolitiasis en condiciones de pastoreo (campo natural) donde 5 de 272 (1.8%) novillos de 14-18 meses enfermaron y murieron evidenciado severa deformación
ventral del abdomen, edema prepucial, polaquiuria, anuria, pérdida progresiva de peso y decúbito. Las principales lesiones fueron uroperitoneo, hidronefrosis y presencia de cálculos de oxalato de calcio en ambos riñones, vejiga y uretra. ---- SUMMARY. - In Uruguay the urolithiasis in cattle has been described in feed-loots. The present study describes an outbreak of urolithiasis in steers grazing native grassland, where 5 out of 272 (1.8%) steers 14-18 months old showed severe ventral deformation of the abdomen, preputial edema, pollakiuria, anuria, progressive weight loss, recumbency, and died. The main lesions were uroperitoneum, hydronephrosis, and calcium oxalate stones in both kidneys, bladder, and urethra.