Currently, serum is used more often than urine to detect prostate specific antigen (PSA). The need for a non-invasive test yielding similar results led us to develop a urine test that uses solar irradiated water as a reactant species. To develop this technology, seven reagents plus one control were produced by exposure of water for 40 days in sunlight to the colors of the visible spectrum through colored cellophane, control being an unwrapped bottle of sterile water. Patients (127) were examined for serum PSA and the urine was tested using the above reagents. A positive urine test was observed with yellow-filtered irradiated water which absorbed at 454nm. Twenty-five of the 45 patients with positive results for the urine test had PSA levels of 0.21-4.0 ng/ml. Thus, this pilot study describes a non-invasive urine test mainly positive in patients with PSA 0.21-4.0 ng/ml.