Untreated 3- and 4-part fractures of the proximal humerus have a poor functional outcome. Open operation increases the risk of avascular necrosis and percutaneous reduction and fixation may be preferable. We report 27 patients, 9 with 3-part and 18 with 4-part fractures, treated by percutaneous reduction and screw fixation. Thirteen of the 4-part fractures were of the valgus type with no significant lateral displacement of the articular segment, and five showed significant shift. Instruments were introduced into the fracture through small incisions so that the fragments could be manoeuvred under the control of an image intensifier, taking advantage of ligamentotaxis as far as possible. A good reduction was achieved in most cases. The average follow-up was 24 months (18 to 47). All the 3-part fractures showed good to very good functional results, with an average Constant score of 91% (84% to 100%), and no signs of avascular necrosis. Good radiological results were achieved in 4-part fractures when impacted in valgus except for one patient with partial avascular necrosis of the head. In those with lateral displacement of the head, revision to a prosthesis was required in one patient because of avascular necrosis and in another because of secondary redisplacement of the fracture. Avascular necrosis was seen in 11% of 4-part fractures. The average Constant score in patients with 4-part fractures who did not need further operation was 87% (75% to 100%).