A group of 55 rottweiler pups was studied from three to 12 months old to assess the incidence and clinical significance of disease involving the palmar metacarpal sesamoid bones. The results of physical examination were correlated with clinical signs of lameness and the results of radiographic examination of the forefeet. Twenty-one dogs became lame during the study and in 12 of them the lameness was attributable to sesamoid disease. However by 12 months of age, the incidence of sesamoid disease as assessed by radiographic changes in the sesamoid bones was 73 per cent (30 of 41 dogs). Six of the 12 dogs which were lame owing to sesamoid disease got better without specific treatment. It was concluded that sesamoid disease can result in clinical lameness in young rottweilers, but that subclinical disease is common.