A total of 1578 patients were treated with potentially curative surgical resection for colon and rectal cancer by one surgeon from 1950 to 1982. Follow-up revealed that 117 (11.5 percent) of 1013 patients with rectal carcinoma eventually presented with clinical evidence of pulmonary recurrence, with or without evidence of spread elsewhere; the corresponding figures for the colon were 20 (3.5 percent) of 565 (P less than 0.001). An analysis of the times to recurrence revealed that half of the lung recurrences were clinically obvious within 32 months for rectal tumors and 34 months for colonic, compared to 22 and 21 months, respectively, for liver recurrences, excluding those with other distant metastases. The slower recurrence rate and the longer survival in patients with recurrences in the lung compared to the liver were statistically significant only for rectal primaries (P less than 0.02 and P = 0.001, respectively). Sixteen patients underwent surgery with curative intention for lung recurrences; four of these remain alive at two, six, 11, and 15 years, and one patient was free of recurrence when he died from other causes 15 months after surgery. The conditional probability survival rate for the 16 patients was 38 +/- 13 percent at five years after recurrence operation.