Pancreatic ductal adenocarcinoma is a dismal disease with a median survival of less than 6 months and an overall 5-year survival rate less than 1%. This bad prognosis is due to early lymphatic and hematogenic dissemination. Effective therapies for locally advanced or metastatic tumors are very limited and curatively resected patients experience relapse in over 80% of cases. Together, these findings reflect the aggressive biology of the disease. Here, we describe molecular mechanisms leading to unrestrained proliferation, insensitivity to growth inhibitory signals, evasion of apoptosis, limitless replicative potential, tissue invasion, metastasis and sustained angiogenesis. Potential therapeutic targets are highlighted.