Nonunion of the distal humerus is rare and diffcult to treat. It presents to surgeon a double challenge : to obtain bony union of the nonunion and to preserve the mobility of the joint. Six patients who had been treated for a nonunion of the distal humerus at National Medical Center from 1980 to 1988 were reviewed. Three of them were extraarticular and the rests were intraarticular fractures. Two had been open fractures. Five had been associated with nerve injury. Senile osteoporosis was noted in two. Four had been initially treated by 0/R and I/F; one, by irrigation, debriment and traction, followed by 0/R and I/F. The average time from the initial treatment to the treatment of nonunion was 20 months, ranging 3 to 44 months. The type of nonunion was reactive in one and nonreactive in five. All patients had pain, instability and limited motion of the elbow. Four who had perfomed surgical treatment for the nonunion were successful in obtaining bony union. Two who had not performed the operation were supported with the elbow brace to relieve the pain and prevent the progression of the deformity. At follw-up(average 21.6 months, ranging 5 to 39 months), functional end result was good in one; fair in four; poor in one, according to the functional rating system of Jupiter et al. In spite of success in union, the functional disability was major long-term problem. The probable causes of nonunion in our cases were unsatisfactory C/R and insufficient immobilization time, incomplete 0/R and inadequate I/F, insufficient postoperative immobilization time, senile osteoporosis, underlying systemic disease, and focal infection in fracture site.