METHODS Randomized controlled study of standard manual therapy given by 31 generalist physicians to 295 patients, in primary care practice. OBJECTIVE To determine whether training primary care physicians in techniques of limited manual therapy would result in improved outcomes for their patients with acute low back pain. BACKGROUND Controversy continues regarding the benefit of spinal manual therapy and the role of highly trained manual therapists in the care of low back pain. Continuing medical education in manual therapy is frequently offered to generalist physicians, but nothing is known of the value and effectiveness of this training. METHODS Thirty-one primary care physicians were trained to provide optimal low back care (enhanced care) and a sequence of eight standard manual therapy techniques. Two hundred ninety-five patients were randomized into two treatment groups: enhanced care alone and enhanced care with manual therapy. Main outcome measures included the Roland-Morris functional disability scale measured over time and patient-reported time to functional recovery, time to complete recovery, and satisfaction with care. RESULTS No differences were found in Roland-Morris scores over time, mean functional days to recovery, days absent from work, or patient satisfaction. More patients receiving manual therapy (21; 14%) had completely recovered after the first visit compared with the control group (8; 6%; P = 0.01). Patients who received more intense manual therapy (four or more maneuvers) had a more rapid return to functional recovery (7.8 days) compared with those who received less intense manual therapy (11.1 days; P = 0.02). CONCLUSIONS Limited training in manual therapy techniques offers very modest benefit compared with high-quality (enhanced) care for acute low back pain. Outcomes may have been modified by failure of some participant physicians to undertake the required sequence of maneuvers. Intensity of manual therapy may be a factor in improving patient outcomes and needs further study.