Ground beef patties containing 10, 20 or 30% textured soy protein (TSP); 10, 20 or 30% mechanically deboned beef (MDB); or combinations of 10% TSP plus 10% MDB, 20% TSP plus 20% MDB, or 30% TSP plus 30% MDB were evaluated for chemical composition, raw product appearance, cooking characteristics and palatability. Raw patties containing 20% or 30% TSP were lighter in color than control (all-beef) patties and therefore received lower overall appearance ratings. Raw patties containing 10% or 20% MDB were significantly darker in color and finer in visual texture than control patties, Raw patties containing combinations of TSP and MDB were generally acceptable in color but too fine in visual texture which lowered overall appearance ratings at the 40% and 60% (TSP plus MDB) substitution levels. Proximate analysis indicated that cooked patties containing TSP retained more moisture but lost more fat than controls, whereas patties containing 10% or 30% MDB lost slightly less fat during cooking than all-beef patties. In comparison with control patties, cooking losses. were lower for patties containing 10% or 30% MDB. Cooking losses were similar for patties containing both TSP and MDB and for patties containing TSP alone. Taste panel evaluation indicated that addition of 20% or 30% TSP decreased flavor desirability and overall palatability ratings. Blended patties containing 20% or 30% MDB had less desirable ratings for taste panel texture than all-beef patties, These data suggest that 10% TSP plus 10% MDB can be added to ground beef patties without significantly affecting overall appearance of raw product, surface area shrinkage during cooking, cooked patty appearance or palatability traits.