Objectives. To determine the concentration of total urinary arsenic (As) in the adult population of two districts in the Tacna region. Materials and Methods. A cross-sectional observational study conducted in the districts of Cairani and Camilaca, in the province of Candarave in the Tacna region, Peru. For the study 103 and 71 urine samples were collected. The concentration of urinary As was determined by the method of microwave digestion and flow injection in atomic absorption spectrophotometry (FIAS-AAS). Results. In the Cairani district, a median urinary arsenic concentration of 601.61 µg/g creatinine (IQR: 407,3-847,1) was obtained; and for Camilaca, a median of 30.24 µg/g creatinine was obtained (IQR: 21,4-39,7). The residents of Cairani and Camilaca exceed 30 and 1.5 times, respectively, the toxicity reference values (TRV) for arsenic. Conclusions. The adult population of the districts of Cairani and Camilaca in the province of Candarave of the Tacna region has urinary As concentrations exceeding the toxicity reference values (TRV) established by the World Health Organization (WHO).