Lymphovascular invasion (LVI) is a prognostic factor in many types of human malignancies, including pancreatic ductal adenocarcinoma (PDAC). However, the prognostic significance of LVI in patients with PDAC who have received neoadjuvant therapy and pancreaticoduodenectomy is unclear. In this study, we analyzed LVI in 212 patients who had received neoadjuvant chemoradiation and subsequent pancreaticoduodenectomy at our institution between January 1999 and December 2007. LVI was present in 61.8% (131/212) of the patients. Of the 131 patients who were positive for LVI, 67 (31.6%) had tumor invasion into lymphovascular spaces without muscle layer (nonmuscular lymphovascular spaces), and 64 (30.2%) had tumor invasion into muscular vessels. Tumor invasion into muscular vessels correlated with higher frequencies of positive resection margin, lymph node metastasis, and locoregional/distant recurrence. Patients with tumor invasion into muscular vessels had significantly shorter disease-free survival and overall survival than did patients who had no LVI or who had tumor invasion of nonmuscular lymphovascular spaces (P<0.01). Tumor invasion into muscular vessels is an independent prognostic factor in patients with PDAC who have received neoadjuvant therapies. Our results showed that tumor invasion into muscular vessels plays an important role in the progression of PDAC and in predicting prognosis in this group of patients.