Time trends in surgical treatment of ulcerative colitis in Stockholm County over the 30-year period 1955 to 1984 were investigated. Four hundred eighty-six patients (263 men and 223 women) were submitted to colectomy with or without proctectomy. In elective cases, proctocolectomy was the procedure of choice until the 1980s, when subtotal colectomy became more common. In acute cases subtotal colectomy was the procedure of choice during the entire period. Major complications developed in 162 patients (33 percent) and 103 (21 percent) underwent another operation. The frequency of major complications increased, with the urgency of intervention being 25 percent in elective cases and 46 percent in acute cases (P less than .001). The postoperative mortality was 1.7 percent in 301 elective cases and 9.2 percent in 185 acute cases (P less than .001). The overall postoperative mortality was 4.5 percent and fell from 13 percent during 1960 to 1964 to 2.0 percent during 1980 to 1984 (P less than .01). In acute cases, the mortality during the same two periods fell from 36 to 3.0 percent (P less than .001). The postoperative mortality for proctocolectomy (2.7 percent) was significantly lower (P less than .01) than for subtotal colectomy (9.0 percent). Seventy-four percent of the patients treated by subtotal colectomy were acute cases, however, with a mortality of 11 percent and only 30 percent of the proctocolectomy cases were acute cases, with a mortality of 6.5 percent.