Background. The goal of this article is to assess the treatment efficacy of partial shoulder arthroplasty after massive proximal humerus resection following pathological fracture or primary tumor, based on the authors' own clinical material. Material and methods. We analyzed 42 cases operated between 1997 and 2005, including 11 patients with primary tumors and 31 with pathological fracture or metastatic disease. A resection ranging from 6 to 12 cm was performed due to the presence of tumor and present or imminent pathological fracture. Partial shoulder arthroplasty was performed subsequently to bone resection. The follow-up time ranged from 2 months to 7 years. Outcome was assessed by X-ray imaging, clinical examination, and the Enneking functional scale. Results. Excellent and very good outcome were obtained in 37 cases, while in 2 cases the outcome was poor. 3 patients died within 7 days after surgery. Infectious complications occurred in 2 patients but resolved after conservative therapy. More than 90% of the patients expressed a positive subjective opinion. Conclusions. Partial shoulder replacement after massive proximal humerus resection was subjectively very acceptable for the operated patients. This high rate of good and excellent outcomes in clinical tests and imaging procedures confirms the usefulness of this method, and makes this kind of treatment a valuable alternative for both the patient and the orthopedic surgeon. Complications, whether early (death) or late (tumor recurrence) result from the normal biology of the tumor.