PURPOSE: Liver surgeons usually recommend against biopsy of colorectal liver metastases because of the risk of local dissemination. To date, only case reports describing this problem have been published. This study is an attempt to quantify the risk of biopsy-related dissemination. METHODS: A multicenter, retrospective review was undertaken of cases of colorectal liver metastases presenting for surgery that had undergone a preoperative biopsy. RESULTS: Two hundred thirty-one cases of colorectal liver metastases presenting for surgery were identified. Forty-three cases had undergone a preoperative biopsy (18.6 percent). Seven patients had evidence of dissemination related to the biopsy, giving a risk of dissemination of 16 percent (95 percent confidence interval, 730 percent). The risk of dissemination was not related to the type of biopsy. Within the follow-up period (median, 21 months), 3 of the 7 cases with evidence of dissemination and 11 of the 35 without dissemination were alive without disease. Twenty-five percent of the 36 cases without dissemination were resected, whereas 6 of the 7 cases with dissemination were resected. CONCLUSIONS: There is a significant risk of local dissemination with biopsy of colorectal liver metastases. In this series this was independent of the type of biopsy. There was no demonstrated effect on resectability or survival, but numbers were small, and the median follow-up was short.