Trim beans and cook, covered, in a small amount of boiling salted water for 10 to 15 minutes or until crisp-tender. Drain and rinse under cool water. Drain and pat dry with paper towels.
Halve tomatoes and place in a large bowl. Add green beans and vinaigrette and toss until well coated. Serve immediately or chill in the refrigerate up to 8 hours.