Laser therapy is able to modulate cell metabolism and accelerate the repair of fracture. Little attention has been given to the effect of laser on bone with osteopenia or osteoporosis. The purpose of our study was to verify the effect of laser therapy in combination with bisphosphonate on osteopenic bone structure. The 35 Wistar female rats used were divided into five groups: (1) sham-operation rats (control), (2) ovariectomized (OVX'd) rats with osteopenia, (3) OVX'd rats with osteopenia treated with laser, (4) OVX'd rats with osteopenia treated with bisphosphonate and (5) OVX'd rats with osteopenia treated with bisphosphonate and laser. Groups 3 and 5 were given daily 6 mg doses of bisphosphonate orally. Groups 4 and 5 underwent low level laser therapy [gallium-aluminum-arsenium (GaAlAs) laser, 830 nm, 50 mW and 4 J/cm(2)] on the femoral neck and vertebral segments (T13-L2). Both treatments were performed over an 8-week period. Rats from the osteopenic control and osteopenic + laser groups presented marked osteopenia. In the osteopenic + bisphosphonate group, the trabecular bone volume in vertebra L2 was significantly greater than in the osteopenic control group. Notably, in the association between laser and bisphosphonate, the trabecular bone volume was significantly greater in vertebrae L2 and T13 and was similar to that in the sham-operation control group. It was concluded that the laser therapy associated with bisphosphonate treatment was the best method for reversing vertebral osteopenia caused by the ovariectomy.