Perfluorooctanesulfonic acid (PFOS) is a ubiquitous substance utilized in industries and a well-known environmental toxicant. PFOS exposure has been associated with testicular cancer, a cancer affecting germline cells. It has remained unclear if PFOS changes the proliferation of cisplatin sensitive and resistant testicular germline cell tumors (TGCTs). It is also unknown if PFOS has different cytotoxic concentrations between cisplatin sensitive and resistant TGCTs. PFOS may causes upregulations and downregulations in cancer associated genes, this has been undetermined. To answer these questions; triplicates were dosed from 0μM – 250μM of PFOS, and a cell viability assay was conducted to determine proliferative changes and the concentrations toxic to cells. RT-qPCR was conducted to determine how mRNA expression of MUC1, FOXB1, SNAP91, and NRN1 changed due to PFOS exposure. It can be concluded that PFOS increases the proliferative potential of both lineages, with the cisplatin resistant cell line increasing at a lower rate in comparison to the cisplatin sensitive cell line. The IC50 of the cisplatin sensitive line and the IC50 of cisplatin resistant line is undetermined, though cisplatin resistant cells likely have a higher IC50. The RT-qPCR did not detect any significant changes in gene expression with respect to PFOS, but MUC1 and SNAP91 had a trend of downregulation.