Since partial thickness tears of the rotator cuff were described well by Codman 1 in 1934, they have been extensively discussed in all kinds of literatures.Partial thickness tears of the rotator cuff are now considered to play a more significant role than previously in inducing patients disability. Partialthickness cuff tears deserve more clinical attention. Both accurate diagnosis and proper surgical repair are very essential. The cognition of partialthickness tears has been deepened in the last decades. In this paper we will review the etiology, classification and clinical evaluation of partial thickness tears of the rotator cuff.