Case series summaryInformation is presented on six new cats with stifle osteochondrosis (OC). In the veterinary literature, there are only four single case reports on cats with this condition. Combining the six new cases with the four previously published cases, we have summarised the current knowledge on stifle OC in the cat. Overall, among the 10 cats, the condition was bilateral in three cats and unilateral in seven. The mean age at presentation was 10.5 months (median 7). Seven cats were male, of which six were castrated, and the three female cats were spayed. Of the cats, five were domestic shorthairs, two were Maine Coons and there was one each of Bengal, Devon Rex and Scottish Fold. The OC lesion affected the lateral aspect of the femoral condyle in seven cats and the medial aspect of the femoral condyle in three cats. All the cats with lesions of the medial aspect of the femoral condyle had unilateral lesions and two of these cats had concurrent medial patellar luxation. All three bilaterally affected cats had lateral femoral condylar lesions. Follow-up of at least 4 weeks was available for 8/10 cats. The lameness resolved or improved in all eight cats: in six cats after surgical debridement of an osteochondritis dissecans (OCD) lesion and in two after conservative management.Relevance and novel informationStifle OC or OCD should be a differential diagnosis for immature cats presenting with stifle lameness, stiffness or difficulty jumping and stifle joint effusions. Patellar luxation may be a concurrent diagnosis.