The desmoplastic nature of the pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME) prevents the infiltration of T cells and the penetration of chemotherapeutic drugs, posing a challenge to the validation of targeted therapies, including T cell immunotherapies. We present an in vitro 3D PDAC-TME model to observe and quantify T cell infiltration across the vasculature. In a three-channel microfluidic device, PDAC cells are cultured in a collagen matrix in the central channel surrounded, on one side, by endothelial cells (ECs) to mimic a blood vessel and, on the opposite side, by pancreatic stellate cells (PSCs) to simulate exocrine pancreas. The migration of T cells toward the tumor is quantified based on their activation state and TME composition. The presence of EC-lining drastically reduces T cell infiltration, confirming the essential role of the vasculature in controlling T cell trafficking. We show that activated T cells migrate ∼50% more than the not-activated ones toward the cancer cells. Correspondingly, in the absence of cancer cells, both activated and not-activated T cells present similar migration toward the PSCs. The proposed approach could help researchers in testing and optimizing immunotherapies for pancreatic cancer.