1. Rinse chicken breasts. Pat dry with paper towels. Place in a plastic bag set into a shallow dish.
2. Combine teriyaki sauce and orange juice concentrate. Pour marinade over the chicken and close the plastic bag. Marinate in the refrigerator for 6 to 24 hours, turning occasionally.
3. Remove from refrigerator and drain the chicken, reserving the marinade.
4. In a small saucepan, bring the reserved marinade to a boil and cook for 2 minutes.
5. Grill the chicken, bone side up, on an uncovered grill directly over medium coals for 20 minutes. Turn the chicken and grill for 20 to 30 minutes more or until tender, brushing often with the reserved marinade. Serve.