BACKGROUND We investigated the effects of the upper-body flexibility exercises on the golf performance of a female amateur golfer. CASE REPORT The participant was a 43-year-old woman who performed a general golf swing exercise (30 min) and an upper-body flexibility exercise (20 min) 3 times a week, for a total of 6 times in 2 weeks. The maximum rotation angle of the upper body was measured using a goniometer. To measure the X-factor, the numerical value was measured after subtracting the rotation angle of the lower-body from the rotation angle of the upper body when the participant stopped making a back-swing top motion. A camera measuring instrument was used to measure the clubhead speed and carry distance of the golf ball when she hit the ball with a no. 7 iron club. After the exercises, the maximum rotation angle of the participant's upper body increased from 40° to 69°, and the X-factor increased from 10° to 24°. The clubhead speed increased from 29.4 m/s to 34.4 m/s, and the carry distance increased from 84 m to 106 m. CONCLUSIONS The participant responded positively to the upper-body flexibility exercises, and there was improved upper-body mobility, X-factor, clubhead speed, and carry distance. Our results showed that upper-body flexibility exercises with a general golf swing exercise for female amateur golfers may improve golf performance.