Charts were reviewed on patients at the Salt Lake Knee and Sports Medicine Clinic who had had a lateral release of the patella. Patients were divided into two groups. Group I contained patients who were entirely satisfied with the procedure, and Group II included patients who were complete failures (defined as a need for further surgical procedures). In Group I, 74 patients were included in the subjective followup. Forty of the 74 patients also had an objective followup, including roentgenograms and a physical examination. Group II contained 43 patients. Results indicated that the most predictable criterion for success was a negative passive patellar tilt. Secondary criteria included a medial and lateral patellar glide of two quadrants or less and a normal tubercle-sulcus angle at 90 degrees of flexion. Patients had less predictable results after an isolated lateral release with a positive (greater than 5 degrees) passive patellar tilt and a three quadrant or greater medial and lateral patellar glide or an abnormal tubercle-sulcus angle at 90 degrees of flexion.