A number of agents have been shown to reduce the risk of fractures in patients with postmenopausal osteoporosis. However, the additional benefits of combination therapy as opposed to monotherapy are uncertain. We performed a MEDLINE search and reviewed the published randomized trials of agents used in combination. Combination therapy results in greater gains in bone mineral density than monotherapy and possibly greater effects on bone turnover. However, none of these studies are large enough or of sufficient duration to determine whether a greater reduction in fracture is achieved. Combination therapy has important cost implications and is likely to be associated with an increased prevalence of adverse events, reduced tolerability and a reduction in adherence. Furthermore, over-suppression of bone turnover as a result of combination antiresorptive therapy might have adverse effects on bone strength, particularly with long-term treatment. Thus, the use of combination therapy for treatment of osteoporosis cannot be recommended on the basis of currently available evidence.