This has been a preliminary report with a short-term follow-up of a small number of observations (28 hips of 24 patients). The follow-ups ranged from 6 to 36 months, with an average of 17.8 months. Only eleven hips (in eleven patients) were followed an average of 8 months after cessation of the treatment. It should be emphasized that this was a "pilot" study, in which no control series was used to determine the natural course of the disease in a comparable clinical setting. Of note was the pain relief, in 19 of 23 patients with moderate to severe pretreatment pain. Also there was an improved function, which suggests that at least in approximately two thirds of the patients there was some clinical benefit from this mode of treatment. In eight hips, clinical conditions did not change; and in two they worsened, requiring further treatment. Eighteen remaining hips were thought to have been benefited by the treatment. Six femoral heads that had already developed varying degrees of collapse (Ficat Type III) collapsed further (1 to 2 mm), and two round heads (Ficat II) progressed to off-round (Ficat III). This preliminary study suggests that further exploration of pulsed electromagnetic fields (PEMFs) is warranted in the treatment of osteonecrosis of the femoral head.