The transmembrane cellular receptor tissue factor (TF) is the primary initiator of the coagulation cascade in man. Expression of TF was determined in 55 specimens of ductal adenocarcinoma of the pancreas and was found to correlate strongly with the degree of histological differentiation. A significant linear trend was observed with stronger immunoreactivity observed in poorly differentiated tumours (chi 2 = 6.69, P = 0.0098). No TF staining was seen in pancreatic samples from normal controls (n = 18). As expression of TF may be associated with tumour progression, its analysis could provide useful prognostic information in patients with pancreatic malignancy.