Displaced fractures of the diaphyseal forearm in children are often treated conservatively, but there is relatively high incidence of redisplacement, malunion and consequent limitation of function. This retrospective study was performed to determine means for minimalising the complications of intramedullary Kirschner (K)-wire fixation used in the treatment of unstable, diaphyseal forearm fractures by pointing out those which most frequently occur with this treatment choice. This treatment method was applied in 48 children with a mean age of 10.3 (range, 5-14) years. A limited open reduction to one or both bones was necessary for insertion of the intramedullary wire in 20 (40%) patients. Although 24 complications, such as pin site infection, loss of forearm rotation, superficial branch of radial nerve palsy, delayed union, nonunion, hardware migration, and K-wire penetration to the opposite cortex, were recorded in 18 patients, 46 patients (96%) had excellent or good, 1 patient (2%) had fair and 1 patient (2%) had poor outcome using the grading scheme adapted by Price. Except for the patient in whom the fracture was not united, the average union time was 6.3 weeks in children less than 10 years and 7.8 weeks in those above 10 years of age. Despite these minor complications, percutaneous intramedullary fixation with K-wires and proper technique is an appropriate, effective and safe operation for unstable diaphyseal fractures of the forearm in children who cannot be treated by closed manipulation.