[Purpose] This study examined the effects of diagonal shoulder training on an individual with secondary impingement due to scapular dyskinesis. [Subject] A 54 year-old female with secondary impingement participated in this study. [Methods] The patient performed diagonal shoulder training in 4-point kneeling, 3 times per day for 20 minutes over a period of 6 weeks. Evaluations of shoulder pain, range of motion, upper trapezius/lower serratus anterior ratio, and impingement were performed before training and at 2, 4, and 6 weeks. [Results] The patient's parameters improved gradually. All parameters returned to normal ranges at 4 weeks. [Conclusion] Diagonal shoulder training is effective for improving dysfunction in individuals with secondary impingement. In addition, this training should be applied for more than 4 weeks.