In the past 6 years, three patients were treated for acute anterior shoulder dislocation which could not be reduced by closed means. Interposition of the labrium was found to be the cause for irreducibility in one patient. The obstructions to reduction in the other two cases were dislocation of the biceps tendon into the joint in one and interposition of the biceps tendon and the greater tuberosity into the joint in the other. The condition manifests in adults more than 40 years old. Redislocation or subluxation has not been observed.