Background. Functional disorder of the shoulder joint on the paretic side is among the more common post-stroke complications. Rehabilitation can be hindered by the associated pain, limited joint mobility, and muscle distension during the period of flaccid paresis (or plegia). The purpose of our study was to evaluate certain shoulder joint structures in post-stroke patients in inpatient rehabilitation, to compare the structural image of the shoulder joint in the affected and healthy limbs, and to identify the impact of rehabilitation on the tested joint structures. Material and methods. In a group of 40 post-stroke patients we performed ultrasonographic examination of the shoulder joints. The study group included patients who were hospitalized from December 2000 to March 2001 in the Department of Rehabilitation at Voivodeship Hospital no. 2 in Rzeszów, Poland. Examinations were performed on the first and last day of hospitalization. Results. Pathological changes were found in the shoulder joints. Over a 3-4-week rehabilitation period some improvement was noted. Conclusions. Changes in shoulder joint structure in post-stroke patients with hemiparesis occur more often on the paretic side (esp. thinning of the rotator cone, the deltoid muscle, and the tendon of the long head of the shoulder biceps, calcification, subluxation in the shoulder joint, and fluid in the bursae). Comprehensive hospital rehabilitation has a positive impact on the tested shoulder joint structures. Ultrasonography is a good method for evaluation of the anatomical structures of the shoulder joint in patients with hemiparesis.