Maximization of the anabolic effects of intermittent administration of parathyroid hormone (PTH) has recently been at the forefront of clinical research in the area of osteoporosis, with the 'anabolic window' concept as its main driving force. The outcome of these attempts, however, has not been encouraging. This article examines whether the concept itself is based on sound evidence, related pathophysiological aspects, and whether the new anti-sclerostin antibodies could have extended anabolic action.