Background: Exosomes are important mediators of intercellular communication, and play pivotal roles in cancer progression, metastasis and chemoresistance. Exosomal membranes are enriched in endosomes-specific tetraspanins (CD63 and CD9). In patients with PDAC, positive correlation between CD9 expression and overall survival (OS) was reported. However, CD63 expression was conserved in all patients without reported prognostic significance. Here, we explored the prognostic significance of CD63 expression using IHC in patients with PDAC of mixed gender and racial background. Methods: Between 2012 and 2016, 49 patients with PDAC treated at Mitchell Cancer Institute had available tissue (pancreatic resected tissue/biopsy [N = 29] or metastatic site biopsy liver, omentum or bone (N = 20)) for CD63 staining using IHC. Two pathologists independently scored the expression of CD63. Staining intensity was graded from 1-3. Staining percentage was estimated in 10% increments. Mean Quick-score (Intensity X Percentage of staining) was calculated. Unpaired t test was used for statistical analysis. Results: Median age was 64 years (range 42-85). 53% are males. 67% white, 27% African Americans (AA) and 6% are other ethnicities. 41% had stage IV disease while 49% had stage I, II and III. Tumor involved the head (51%), body (20%) and tail (29%). The mean CD63 Q score is slightly higher in AA compared to white (157 vs 149, P = 0.76). The mean CD63 Q score is higher in the pancreatic tissues compared to metastatic sites tissues (185 Vs 102, P = 0.0002). In our cohort, patients with mean CD63 Q score > = 140 had longer median OS compared to patients with mean Q score of < 140 (19 months Vs 3 months, P = 0.0003) and progression free survival (PFS) (12 months vs 1 month, P = 0.0043). Conclusions: In our cohort of patients with PDAC, there was no racial difference in CD63 expression between white and AA. The expression of CD63 is higher in the pancreas compared to metastatic sites (liver, omentum and bone). There is positive correlation between CD63 expression and PFS and OS. To our knowledge, this is the first study to show prognostic significance of CD63 expression in patients with PDAC using IHC.