The aim of the study was to assess the frequency of synchronous colorectal and renal cancers among our patients. To this end we reviewed 781 consecutive patients operated on for colorectal carcinoma in our institution. Three patients (0.4%) had diagnosis of synchronous renal-cell cancer during the work-up for their colorectal primary tumours. The colon and rectum are frequently affected by multiple malignant tumours. Second primaries are not frequently associated with colorectal cancer. On the other hand, renal cell carcinoma has been described as being associated with other synchronous malignancies in up to 27.4% of cases. A recent report has described a 4.8% incidence of synchronous colorectal and renal carcinomas, which is much higher than that previously reported in the literature (0.03-0.5%). We found a 0.4% incidence of simultaneous colorectal cancer and renal cell carcinoma. The latter was invariably asymptomatic and diagnosed during the work-up for the colorectal cancer. We are unable to confirm the observation of a higher than expected incidence of synchronous colorectal and renal neoplasms. Nevertheless, the surgeon should be conscious of this association, when considering renal lesions detected during the work-up for colorectal cancer.