Primary signet-ring cell carcinoma is an uncommon malignancy arising in the urinary bladder. The authors report 12 cases collected at their institution. Median age for the ten men and two women was 58 years; the most frequent presentation was hematuria. In two of nine cases no mucosal lesion was cystoscopically visible. Eleven tumors were of nonurachal origin and one of urachal. At diagnosis, one tumor was stage B, two stage C, seven stage D, and two stages unknown. Nine of 12 patients were dead of disease (range, 1-16 months; median, 9 months), 1 alive with metastatic disease, 1 alive and well, and 1 dead of an unrelated cause. From a literature review, the authors accepted 35 cases that met their criteria and combined them with their 12 cases for statistical analysis. Prognosis was worse with a pure diffuse versus a mixed tumor (P = 0.004) and for nonurachal versus urachal origin (P = 0.005). The difference in five-year survival rates between stages B and D disease (P less than 0.05) was also statistically significant.