Preheat broiler. Spread 1/4 cup tuna salad on each slice of rye bread. Sprinkle each sandwich with 1/4 cup shredded Havarti. Arrange sandwiches on small baking sheet.
To broil, place baking sheet with sandwiches 4 to 5 inches from the heat. Broil for 2 to 3 minutes or until cheese is melted and slightly browned. Makes 4 servings.