FOLFOX-4 (folinic acid/5-fluorouracil/oxaliplatin) chemotherapy is used to treat patients with colorectal liver metastases. We aimed to assess hepatic histopathological responses to neoadjuvant FOLFOX-4 chemotherapy in patients with colorectal liver metastases. We selected all patients (n = 54) treated with FOLFOX-4 for colorectal liver metastases between June 2002 and June 2005. Only 25 underwent hepatectomy and formed the study group. Histological responses were assessed in the study group and a matched control group (n = 25) that did not receive neoadjuvant chemotherapy. The median (IQR) body mass index in the study and control groups was 24 (22-26) and 24 (23-25) kg/m(2), respectively, (P = NS). Complete histological resolution of tumour occurred in six (24%) patients in the study group. Median residual tumour cellularity was less (35 vs 70%) and fibrosis greater (50 vs 5%) in patients in the study group when compared with controls (P < 0.001). The liver surrounding the tumour was steatotic in 17 (68%) patients in the study group and five (20%) controls (P = 0.001). Hepatic sinusoidal dilatation was more pronounced in patients in the study group than in controls (P < 0.001). The response to FOLFOX-4 was associated with tumour necrosis, fibrosis and inflammation. More than two thirds of patients undergoing hepatectomy after FOLFOX-4 had steatosis despite being non-obese.