The Polilight located stains that were not apparent to the naked eye. It was comparable to the acid phosphatase (AP) test for seminal fluid and Phadebas paper for saliva. A comparative study of the AP test and Polilight on 40 casework exhibits yielded 1 false-negative result when using the Polilight. In a series of mock casework exhibits, the Polilight successfully located saliva stains for DNA analysis. The sensitivity of luminol for detecting potential bloodstains was greater than that of Polilight; however, the Polilight was useful for a bloodstain that may be concealed with paints. Overall, the authors conclude that the Polilight is a relatively safe, simple, noninvasive, and nondestructive technique that is suitable for forensic casework. The Polilight used in this study was a PL 500 (Rofin). Fresh seminal fluid, saliva, and blood were stained onto cotton swabs and a range of colored fabrics. Serial dilutions of seminal fluid, saliva, and blood were performed with distilled water to produce a concentration of 1:100,000 in a final volume of 500 ml. AP testing of 40 casework exhibits, after examination with Polilight, was performed in accordance with standard procedures. Other procedures described in the testing are the effects of laundry detergents under Polilight; a comparison of saliva and blood to other fluids under Polilight; the recovery of DNA from saliva stains identified with Polilight; the identification of mock casework saliva stains using Polilight; and the examination of the effects of potentially interfering substances or conditions on the identification of bloodstains using Polilight. 3 tables, 10 figures, and 18 references