Background: Pancreatic ductal adenocarcinoma (PDAC) is highly drug resistant with no change in therapeutic approach for the last decade. The PDAC tumor microenvironment (TME) is highly desmoplastic and associated with altered treatment response. Our group previously identified 9 distinct cell types in human PDAC tumors using single-cell RNA-sequencing, demonstrating a diverse TME. However, the TME of in vitro organoid PDAC models remains underexplored. We initiated characterization of the TME from PDAC patient derived organoids (PDOs) to establish a working model for accurate drug sensitivity testing. Methods: We performed immunofluorescence (IF) staining on whole-mount early passage ( Citation Format: Mei Gao, Charles J. Bailey, Megan M. Harper, Michael J. Cavnar, Prakash Pandalai, Shadi A. Qasem, Joseph Kim. Identification of tumor microenvironment components in patient-derived pancreatic ductal adenocarcinoma organoids [abstract]. In: Proceedings of the AACR Special Conference on the Evolutionary Dynamics in Carcinogenesis and Response to Therapy; 2022 Mar 14-17. Philadelphia (PA): AACR; Cancer Res 2022;82(10 Suppl):Abstract nr A029.