Although plastic garbage bags are routinely submitted to forensic laboratories, bag examination has been limited to latent fingerprint analysis. In certain circumstances, determining whether the submitted evidence can be associated with similar bags recovered from a suspect may be crucial to the investigation. Physical comparison requires an understanding of the manufacturing process used to produce plastic garbage bags. In examining plastic garbage bags, a large lightbox can be used to transmit light through the bag. This examination consists of comparing and evaluating class characteristics of relative colors, dimensions, gauges, cuts, heat seals, slit seals, and printing. In addition, the examination should focus on the arrangement of die lines and on random arrangements of fisheyes, arrowheads, tigerstripes, streaks, pigment density variations, and tears. The significance of the quality and quantity of repeatable class characteristics and the quality and quantity of nonrepeatable random arrangements of characteristics can be compared and evaluated to reach a conclusion about the questioned evidence bag versus known standard bags. 6 references and 14 figures