Guidelines portray low back pain (LBP) as a benign self-limiting disease which should be managed mainly by primary care physicians. For the German health care system we analyze which factors are associated with receiving specialist care and how this affects treatment. This is a longitudinal prospective cohort study. General practitioners recruited consecutive adult patients presenting with LBP. Data on physical function, on depression, and on utilization of health services were collected at the first consultation and at follow-up telephone interviews for a period of 12 months. Logistic regression models were calculated to investigate predictors for specialist consultations and use of specific health care services. Large proportions (57%) of the 1342 patients were seeking additional specialist care. Although patients receiving specialist care had more often chronic LBP and a positive depression score, the association was weak. A total of 623 (46%) patients received some form of imaging, 654 (49%) physiotherapy and 417 (31%) massage. Consulting a specialist remained the strongest predictor for imaging and therapeutic interventions while disease-related and socio-demographic factors were less important. Our results suggest that the high use of specialist care in Germany is due to the absence of a functioning primary care gate keeping system for patient selection. The high dependence of health care service utilization on providers rather than clinical factors indicates an unsystematic and probably inadequate management of LBP.