['The aim was to investigate the outcomes associated with venous thromboembolism (VTE) among irresectable pancreatic cancer patients.', 'This is a follow-up study of consecutive irresectable cancer patients, treated and followed up in clinical trials between December 2001 and December 2004 in order to evaluate the prognostic impact of symptomatic VTE on clinical outcomes, such as response to treatment, progression-free survival (PFS) and overall survival (OS).', 'Among 227 irresectable pancreatic cancer patients, with Eastern Cooperative Oncology Group performance status (ECOG-PS) < or = 2, 59 (26.0%) patients developed a VTE. A synchronous VTE occurred in 28 (12.3%) patients, while a VTE during chemotherapy was observed in 15 (6.6%) patients, and 16 (7.0%) patients experienced both events. Presence of synchronous VTE was associated with a higher probability of not responding to treatment (odds ratio 2.98, 95% CI 1.42-6.27, P = 0.004), but showed no effect on both PFS and OS at least at multivariate analysis. Occurrence of a VTE during chemotherapy showed a statistically significant effect on PFS (hazard ratio [HR] 2.59, 95% CI 1.69-3.97, P < 0.0001) and OS (HR 1.64, 95%CI 1.04-2.58, P = 0.032).'] Does venous thromboembolism predict poor prognosis in irresectable pancreatic cancer patients?