Abstract Disclosure: K.C. Yuen: Consulting Fee; Self; Novo Nordisk, Neurocrine, Crinetics, Recordati, Ascendis, Chiesi. Grant Recipient; Self; Ascendis, Corcept Therapeutics, Chiesi, Sparrow. Speaker; Self; Recordati, Novo Nordisk. W. Huang: Advisory Board Member; Self; Chiesi, Novo Nordisk, Neurocrine, Crinetics, Recordati. Speaker; Self; Chiesi, Recordati. M. Fleseriu: Consulting Fee; Self; Camurus, Crinetics, Recordati. Grant Recipient; Self; Crinetics (via institution). E.B. Geer: Advisory Board Member; Self; Chiesi, Crinetics. Consulting Fee; Self; Crinetics. T. Araki: Advisory Board Member; Self; Chiesi. A. Labadzhyan: None. P.U. Freda: None. A.G. Ioachimescu: Consulting Fee; Self; Crinetics, Camurus, Xeris. E.A. Christofides: Advisory Board Member; Self; Chiesi. Speaker; Self; Chiesi. J. Sisco: Advisory Board Member; Self; Novo Nordisk. Speaker; Self; Pfizer, Inc.. N.R. Biermasz: None. J.A. Crompton: Employee; Self; Chiesi. M.E. Molitch: Consulting Fee; Self; Chiesi, Takeda, Sention, Jansen Pharmaceuticals. Background: MACRO is a non-interventional, prospective, disease-based cohort registry that collects data on patients with active acromegaly. We report data of real-world experience with oral octreotide capsules (OOC) using paired data from acromegaly patients and their physicians. Methods: Patients (pts) and physicians completed questionnaires at enrollment and every 3 mos (up to 3 yrs) on demographic, disease activity, treatment information, ratings of symptom and biochemical control (“well”, “partially”, “not”, “unsure”), and patient-reported outcomes. Descriptive statistics were analyzed. Results: Out of 230 pts, 32 (14%) received OOC at baseline [30 monotherapy; 1 combination w/pegvisomant (PEG), 1 w/cabergoline (CBG)] and 26 (11%) initiated post-baseline [20 monotherapy; 6 combination (3 w/CBG; 1 w/PEG; 1 w/PEG&CBG; 1 w/bromocriptine)]. Reasons for initiating OOC included patient preference (13, 50%) and lack of symptom control (10, 38%) or biochemical control (7, 27%). Starting dose was unknown, 40, 60, or 80mg/day in 1 (4%), 20 (77%), 2 (8%), and 3 (12%) of newly-initiated pts. Mean (±SD) time on OOC was 19.7±18.1 mos with 42 (72%) receiving for ≥ 6 mos. Last recorded daily dose (n, %) for pts remaining on OOC monotherapy (n=31) was 20 (1, 3%), 40 (16, 52%), 60 (5, 16%), and 80mg (9, 29%). In pts with available IGF-I levels at last follow-up, 81% (39/48) overall and 100% (33/33) on monotherapy were ≤ 1x ULN (mean ± SD = 0.8 ± 0.4 for overall group). Among all pts, 19 (33%) discontinued OOC [5 (9%), 3 (5%), and 9 (16%) for lack of biochemical control, symptom control or adverse events, respectively]. Median (range) time on OOC prior to discontinuation was 5 (2-72) mos. In monotherapy pts discontinued solely for lack of biochemical and/or symptom control, 3/4 (75%) were receiving < 80mg/day. Of 39 pts remaining on OOC-based therapy (31 monotherapy, 8 in combination), 34 (87%) were biochemically well-controlled at last follow-up and 24/34 (71%) were also symptomatically well-controlled per patient report. In the 16 pts initiated on OOC post-baseline and remaining on therapy (8 monotherapy; 8 in combination), 12 (75%) were biochemically well-controlled. Patient-reported symptom control was maintained or improved in newly-initiated pts in 11/16 (69%). Last patient reported symptom control in newly-initiated OOC pts (n, %) was well (8, 50%), partially (4, 25%), not controlled (1, 6%) or unsure/not reported (3, 19%). Conclusions: Most patients were on OOC as monotherapy at 40mg/day and maintained or achieved biochemical control. Discontinuation reasons were consistent with clinical trial experience. In over half of patients discontinuing OOC due to inadequate biochemical or symptom control, dose titration up to 80mg/day was not implemented. Approximately half of patients receiving OOC reported well-controlled symptoms. Presentation: 6/2/2024