Osteoporosis in men is a common but often overlooked disorder by clinicians. The criterion for osteoporosis diagnosis in men is similar to that in women—namely, a bone mineral density (BMD) that is 2·5 standard deviations or more below the mean for the young adult population (aged 20–29 years; T-score –2·5 or lower), measured at the hip or lumbar spine. Sex steroids are important for bone health in men and, as in women, oestrogens have a key role. Most men generally have bigger and stronger bones than women and typically have less bone loss during their lifetime.