We investigated the safety and efficacy of circadian chronotherapy via the hepatic artery(chrono-HAI)as a prehepatectomy chemotherapy for initially unresectable colorectal liver metastases. Five-day course of chrono-HAI using 5-FU, l-LV, and L-OHP plus systemic panitumumab with 9-day interval were administered to 24 patients with failure for previous chemotherapy. Response rate and Grade 3 adverse effect(AE) were 63% and 54%, respectively. Among 22 patients( excluding 2 CR patients), conversion surgery could be performed in 10(45%). Two-year overall survival of patients with surgery (58%)was longer in those without(20%, p=0.057). Although incidence of AE was a bit high, chrono-HAI plus systemic panitumumab is an effective prehepatectomy chemotherapy for patients with aggressive colorectal liver metastases.