A passive shoulder exerciser constructed to reciprocably move a patient's arm back and forth through an arc of up to 180.degree. for providing flexion and abduction of the shoulder. The shoulder exerciser includes a base, an electric drive motor, and an arm holder for the patient's arm, mounted to the drive motor for reciprocal movement by the drive motor through an arc of up to 180.degree.. The arm holder is slidably and pivotably mounted such that during use of the exerciser, a patient's arm may slide towards and away from the body and pivot along two pivot points to allow the shoulder joint to follow a natural anatomical range of motion. The shoulder exerciser is adjustable for use with either shoulder. Additionally, the shoulder exerciser is adjustable for a patient's height, arm length, and is adjustable with respect to speed and range of motion.