The objective of this study was to report long-term clinical and radiographic outcomes following arthroscopic reparative treatment - flap removal, curettage, and osteostixis of subchondral bone - in dogs with humeral trochlea osteochondritis dissecans (OCD). Dogs were included in this retrospective multicenter case series if they had a computed tomography diagnostic of humeral trochlear OCD, with or without medial coronoid disease, that was treated by arthroscopic reparative technique, and a detailed follow-up at least 6 mo postoperatively. The latter included a clinical examination, assessment of lameness, measurement of the brachial circumference and elbow amplitude, International Elbow Working Group (IEWG) radiographic score, owner-completed canine brief pain inventory (CBPI) score, and visual analogue scale (VAS) rating. A generalized linear model and tests for symmetry and marginal homogeneity were used to compare data. Twenty-three dogs (30 affected elbows) were included. Long-term (median: 22 mo; range: 6 to 98 mo) postoperative lameness, CBPI, VAS, joint distension, and pain scores were significantly improved compared with the preoperative values. Long-term postoperative range of motion and brachial circumference did not reveal any significant difference between OCD-affected and unaffected elbows. Long-term IEWG scores were similar to preoperative values in 56% of elbows and had progressed by 1 grade in 44%. Long-term complications included persistent Grade-1 lameness and occurred in 23% of dogs. Long-term outcomes based on lameness and CBPI scores were considered excellent in 67% of dogs, good in 27%, and intermediate in 6%. Arthroscopic treatment is thus a suitable surgical procedure for OCD of the humeral trochlea in dogs and provides good long-term results.