Congenital pseudarthrosis of the olecranon is a rare condition. Three isolated cases with bilateral presentation, different treatment modalities and variable outcome were reported in the orthopaedic literature. In this presented case a pseudarthrosis of the right olecranon in a 13-year-old boy was treated by pseudarthrosis resection, bone graft interposition and tension band osteosynthesis. Hardware removal was performed nine months after the initial procedure. At 6-year follow-up at the end of growth, the patient has no pain and a free range of motion of his dominant right elbow. This (to our knowledge) first case of unilateral pseudarthrosis of the olecranon had an excellent clinical result with stable fixation and support of bone healing by a bone graft interposition.