Objective: This study was undertaken to correlate postoperative survival of patients with ulcerative colitis-associated colorectal cancer with the stage, configuration, size, and mucin content of the tumor. Summary Background Data: The factors influencing prognosis in colorectal cancer in the general population are well accepted, but less is known about their influence in cases of colorectal cancer associated with ulcerative colitis. Methods: The authors reviewed the records of 102 patients with ulcerative colitis-associated colorectal cancer admitted to The Mount Sinai Hospital between 1959 and 1988. Tumors were classified on independent pathologic review according to histologic stage, configuration, size, and mucin content. Comparisons among survival curves were tested by the generalized Wilcoxon test. Cox regression models were used to examine the joint effects of selected clinicopathologic features on postoperative survival rates. Results: Complete follow-up was obtained for 93 patients (92%). Overall 5-year actuarial survival was 52%. When factors were analyzed one at a time, survival was significantly poorer among patients with advanced cancer stage, larger tumor size, infiltrating and ulcerating configuration, and high mucin concentration. On multivariate analysis by the Cox regression model, however, only cancer stage emerged as a factor independently predicting survival. Conclusions: For colitis-associated colorectal cancers, as for noncolitic cancers, histologic stage is the most important variable determining postoperative survival. The distribution of stages in our series and the survival rates within each stage did not differ appreciably from the distributions and survival rates reported for noncolitic colorectal cancers.