['Manipulation under anesthesia (MUA) as treatment for idiopathic frozen shoulder increases motion, provides pain relief, and restores function, but it is unclear whether the improvements persist long term.', 'We therefore investigated whether (1) ROM was restored, (2) pain was relieved, and (3) function was restored and maintained after several decades in patients with idiopathic frozen shoulder treated by MUA.', 'We followed 15 patients (16 shoulders; 12 in women) at 3 months, 7 years, and 19 to 30 years after MUA for frozen shoulder. Their mean age at MUA was 48.5 years. Four patients had diabetes. The time between the onset of symptoms and manipulation averaged 7.6 months. We determined pain by a patient-generated VAS (range, 0-10; 0=none, 10=maximal). We recorded ROM and Constant-Murley scores at last followup.', 'At 7 years, improvement had occurred in forward flexion to 155°, abduction to 175°, external rotation to 51°, and internal rotation to the T7 level. During the next 16 years, ROM deteriorated by 8° to 23° at last followup, but still equaled ROM of the contralateral shoulder. On the VAS, pain at last followup averaged 1.5 with exertion, 0.3 at rest, and 0.8 at night. The Constant-Murley score was 70 (range, 34-88); 12 patients reached the age- and sex-adjusted normal Constant-Murley score.'] Do motion and pain relief remain 23 years after manipulation under anesthesia for frozen shoulder?