To determine the effectiveness of exercise therapy (ET) compared with ET with adjunctive manual therapy (MT) for people with hip osteoarthritis (OA); and to identify if immediate commencement of treatment (ET or ET+MT) was more beneficial than a 9-week waiting period for either intervention. Assessor-blind randomized controlled trial with a 9-week and 18-week follow-up. Four academic teaching hospitals in Dublin, Ireland. Patients (N=131) with hip OA recruited from general practitioners, rheumatologists, orthopedic surgeons, and other hospital consultants were randomized to 1 of 3 groups: ET (n=45), ET+MT (n=43), and waitlist controls (n=43). Participants in both the ET and ET+MT groups received up to 8 treatments over 8 weeks. Control group participants were rerandomized into either ET or ET+MT groups after 9 week follow-up. Their data were pooled with original treatment group data: ET (n=66) and ET+MT (n=65). The primary outcome was the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function (PF) subscale. Secondary outcomes included physical performance, pain severity, hip range of motion (ROM), anxiety/depression, quality of life, medication usage, patient-perceived change, and patient satisfaction. There was no significant difference in WOMAC PF between the ET (n=66) and ET+MT (n=65) groups at 9 weeks (mean difference, .09; 95% confidence interval CI -2.93 to 3.11) or 18 weeks (mean difference, .42; 95% CI, -4.41 to 5.25), or between other outcomes, except patient satisfaction with outcomes, which was higher in the ET+MT group (P=.02). Improvements in WOMAC, hip ROM, and patient-perceived change occurred in both treatment groups compared with the control group. Self-reported function, hip ROM, and patient-perceived improvement occurred after an 8-week program of ET for patients with OA of the hip. MT as an adjunct to exercise provided no further benefit, except for higher patient satisfaction with outcome.