One hundred thirty-six patients with impingement syndrome and rotator cuff disease who were treated nonoperatively from 1987 to 1991 were reviewed to identify findings at initial presentation that correlated with final outcome. Mean followup was 20 months (range, 6-41 months). All patients received initial conservative treatment. The results were analyzed in 2 groups. Group I consisted of the entire 136 patients with a minimum 6-month followup. Group II consisted of a subgroup of 68 patients with at least an 18-month followup. The overall results in Group I were 66% excellent and good and 34% fair and poor. For Group II, the overall results were 76% excellent and good and 24% fair and poor. For the Group II patients, a distribution of clinical findings at the 6-month followup demonstrated only 46% excellent and good results, indicating that the clinical result improves significantly as followup duration increased. Patient characteristics and prognostic factors that were associated with an unfavorable clinical outcome included a rotator cuff tear > 1 cm2, a history of pretreatment clinical symptoms for > 1-year duration, and significant functional impairment at initial presentation. Factors not associated with clinical outcome included patient age, occupation, gender, associated instability, dominance, chronicity of onset, active range of motion, or specific treatment modalities. Early operative intervention is recommended for patients with poor prognostic factors to avoid a protracted clinical course.