Physicochemical parameters such as pH, color and lipid oxidation are gross indicators of meat quality, as well as sensory attributes (Shahidi, 1994). Bovine trimmings are the main ingredient of patties produced worldwide. Since this meat results from mechanical disruption of several muscles, assessing microbiological markers (total mesophilic counts,Escherichia colicounts) and absence of pathogenic strains become mandatory and are used as trade standards. Irradiation may be applied to packaged products extending their shelf-life and improving their microbiological safety with minimal effects on their chemical composition, nutritional and sensory properties. Food spoilage microorganisms are generally very susceptible to irradiation. Even at low dose, irradiation can initiate or promote lipid oxidation resulting in undesirable off-odors and flavors (Lescano et al. 1991) and can produce a variety of color changes. The objectives of the present work were to assess the use of moderate doses of irradiation (2 and 5 kGy) as a tool to reduce the microbial load without altering the quality attributes of bovine trimmings and of patties made of irradiated trimmings. The study included microbiological indicators during 30 days of storage (coliforms, pseudomonas andmesophilicaerobics counts); physicochemical indicators (pH and color) and sensory changes during a 180 day storage period at freezing temperatures.