Thirty-five patients with sequential fractures of both hips were studied prospectively. The second hip fractures occurred more commonly if the patients were institutionalized, if they suffered from concomitant neurologic diseases such as previous stroke or Parkinsonism, or if there was biochemical evidence of osteomalacia. Twelve patients sustained the contralateral hip fracture within 12 months of the first one. There was a significant correlation between biochemical evidence of osteomalacia and early occurrence of the second hip fracture. Although rehabilitation was difficult for such patients, it was possible with a longer period of intensive physiotherapy; only three patients were not able to walk upon discharge from the hospital after the second hip fracture.