Toxicity assessment of large numbers of oil sands process-affected waters (OSPW) are needed in order to reclaim mined oil sands aquatic reclamation scenarios, such as End Pit Lakes (EPLs). Conventional toxicity testing using whole animals can make this process extremely costly, thus alternatives are being sought. A non-lethal bioassay is being developed and validated to aid in supporting reclamation planning. This study employed six fish cell-lines (WF-2, GFSk- S1, RTL-W1, RTgill-W1, FHML, FHMT) in 24h viability assays for rapid fluorometric assessment of cellular integrity and functionality. Eight ml from forty-nine OSPW samples received from Syncrude Canada Ltd. were mixed with 2 ml of 5X concentrated L-15/ex minimal media solution and used to expose cells. After 24h exposure to OSPW samples, significant decreases in cell viability as measured by Alamar blue (AB) were seen in all cell lines for a number of samples. Bioassays were done in blind, but when OSPW chemical composition was revealed there was a consistent correlation between decreasing cell viability and increasing naphthenic acid (NA) concentrations present in the samples. Regression analysis yielded correlation coefficients2 as high as 0.6171 (WF-2 cell line, AB; p<0.0001). NAs have been identified as the chief toxicants in OSPW. Therefore, a fish-cell line bioassay sensitive to fluctuations in NA concentration could be a tool integral to the safe implementation and biomonitoring of wet reclamation landscapes in the Athabasca oil sands region, such as EPLs.