TOTAL PROSTATIC SPECIFIC ANTIGEN LEVELS AMONG SUBJECTS EXPOSED AND NOT EXPOSED TO ARSENIC IN DRINKING WATER Background: There is an association between arsenic exposure and prostatic cancer mortality. Aim: To analyze and to compare the serum levels of Total Prostatic Specific Antigen (TPSA) in asymptomatic men of a rural zone, exposed and not exposed to high concentrations of Arsenic (As) in drinking water. Material and methods: The study included 161 men that were subjected to a clinical evaluation, serum TPSA determination and a trans rectal ultrasonography. Exposed and non-exposed subjects were divided in groups GA, GB and GC according to TPSA levels   (10.1 ng/ml respectively). Results: Exposed and non-exposed subjects had similar TPSA levels. Among exposed subjects, 88.2, 8,8  and 3% were ascribed to groups GA, GB and GC respectively. The figures for non-exposed subjects were 90. 6, 6,3 and 3,1%.  The area under the receiver operating characteristic (ROC) curve for TPSA in exposed and non-exposed subjects was 0.64 (95% confidence intervals (CI) 0.40-0.9) and 0.71 (95% CI 0.6-0.8) respectively. Conclusions: No differences in TPSA levels between subjects exposed and non-exposed to arsenic were observed in this study.