Biodegradable cases are being developed as an alternative to the existing cases for the M18/M83 smoke grenade. The existing M18/M83 case uses metal components that are not consumed during use and cannot be left on the ranges due to potential environment concern. Approximately 500,000 cases are used per year and left unrecovered as litter on battlefields and training areas. A replacement cases / covers were fabricated from polyhdroxyalkanoate (PHA), a biodegradable polymer and studied in soil by respirometry and weight loss methods. The PHA samples were injection molded into tensile bars and then prototype cases/covers were also fabricated and used in the studies. The soil respirometry test utilized American Society for Testing and Materials (ASTM) method, D5988 - 18 Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials in Soil. This was a Tier I test to confirm that biodegradation was occurring with carbon converted in carbon dioxide to yield percent biodegradation or mineralization. Samples were run in triplicate and Kraft paper and polyethylene were used as positive and negative controls. A Tier II test was also performed utilizing a modified test of the American Association of Textile Chemists and Colorists (AATCC) Test Method 30-2004, Antifungal Activity, Assessment on Textile Materials: Mildew and Rot Resistance of Textile Materials. Soil, compost and sand were combined with water and samples in triplicate were buried in the mixture. Samples were removed each week for 12 weeks and the weight loss was recorded. The samples were evaluated for mechanical properties after withdrawing samples from the soil burials. These cases did prove to be biodegradable in the soil and are promising alternatives that have comparable performance to the existing cases.