296 Background: PETCAM was a randomized trial evaluating the effect of PET-CT compared to conventional imaging (control) on the surgical management of patients with resectable colorectal cancer liver metastases (CRLM). It concluded that PET-CT did not result in frequent change in surgical management (8·0%, 21/263) with only 2·7% (7/263) avoidance of liver resections. In this study we conducted a cost analysis of these two arms up to one year following randomization. Methods: Health care utilization was collected for all study participants. Unit costs for hospitalization, physician services, chemotherapy and outpatient radiological and endoscopic procedures were obtained from administrative databases. Cost analysis was undertaken from the perspective of a third-party payer (i.e., Ministry of Health). Mean cost with its 95% credible interval was estimated using a Bayesian approach. Results: The estimated mean cost per patient in the PET-CT arm was CAN $45,454 (min-max: 1,340-181,420) and in the control arm, CAN $40,859 (min-max: 279-293,558), with a net difference of CAN $4,327, 95% credible interval -2,207 to 10,614. The primary cost driver was cost of hospitalization for liver surgery (+ $2,997 CAN for the PET-CT arm), mainly due to a longer length of hospital stay for the PET-CT arm compared to control (median 7 days vs. 6 days, P= 0·034) and a higher rate of postoperative complications (52/255, 20% vs. 13/128, 10%, P = 0·014). Baseline characteristics were similar between groups, including a similar number of liver segments involved with cancer, number of segments resected and type of liver resection performed. Conclusions: PET-CT does not appear to provide a significant clinical benefit in the surgical management of patients with resectable CRLM and it is not cost saving compared to control.