In this prospective study we evaluated the functional and radiological results obtained in 62 patients who had been treated for fracture of the humeral head by internal fixation with a cloverleaf plate. They were examined postoperatively, after 14 weeks and after an average follow-up of 75 weeks. Nine patients (14.5%) had dislocated 2-part fractures, 36 had 3-part fractures (58%; additional dislocations of the greater or lesser tubercle), 13 patients (21%) had 4-part fractures and 4 (5.6%) had luxation fractures of the humeral head. Early functional physiotherapy was started on the third day after surgery. The complications observed were: subcutaneous infection (2 cases; 3.2%), haematoma (2 cases; 3.2%), temporal paraesthesia of the axillary nerve (1 case; 1.6%). Only 4 (6.5%) patients suffered from necrosis of the humeral head (partial in 3, total in 1); in 2 cases (3.2%) we switched to a different procedure; in both these patients a humeral head prosthesis was implanted; in both these cases the clinical result was poor because of progressive varus dislocation. To improve mobility we performed arthrolysis in 8 cases (12.9%) and acromioplasty in 10 (16.1%), in addition to removing the plates after fracture consolidation confirmed by X-ray examination. In the present study those of our patients who had been treated with open reduction and internal fixation with a cloverleaf plate achieved average Neer scores of 77+/-13 and average Constant scores of 72.4+/-18, and the rates of complications or revisions were low. "Good" or "very good" results were obtained according to the Constant score in 59% of the treated patients. Even patients with complex 4-part fractures had average Constant scores of 72.7 points ("good"). The accuracy of the refixation of the greater tubercle, sufficiently low fixation of the cloverleaf plate and avoidance of varus position when the humeral head was repositioned were significant parameters influencing the functional outcome in our patients.