Severe unilateral ptosis with poor levator function has previously been treated with maximal levator muscle resection or bilateral or unilateral frontalis suspension. One of us (R.L.A.) has developed a technique called "Whitnall's sling," where only the levator aponeurosis is resected, preserving Whitnall's ligament and its attachments. Whitnall's ligament and the underlying resected levator muscle are sutured to the superior portion of the tarsal plate. This surgery preserves levator muscle, Müller's muscle, and Whitnall's ligament without altering the structures that produce the three-layer tear film. In 69 eyelids operated on between July 1976 and July 1986, in which a minimum of 1 year of follow-up by one of use was obtained, results have been satisfactory and directly related to levator function. We believe this technique to be anatomically and physiologically superior to "maximal levator resection" with similar long-term results. More recent results have shown that the addition of a 5-mm superior tarsectomy provides an additional elevation of 1 to 1.5 mm. Whitnall's sling is best suited for cases where the opposite fissure height is 9 mm or less and levator function of the ptotic eyelid is 3 to 5 mm.