Risk factors for vertebral fractures due to osteoporosis were evaluated in 105 consecutive male patients over a four-year period. An equal number of men with Paget's disease, matched by age, who concurrently attended the same subspecialty clinic served as control subjects. The relative risk for osteoporosis, estimated by the odds ratio, was increased among those who smoke cigarettes (relative risk = 2.3; p = 0.01), drank alcoholic beverages (relative risk = 2.4; p = 0.02), or had an associated medical disease known to affect calcium or bone metabolism (relative risk = 5.5; p less than 0.001). Obesity was protective (relative risk = 0.3; p less than 0.001). As assessed by a multiple logistic model, the risk associated with smoking and drinking increased with age. The effects of these four major risk factors were largely independent of one another and were cumulative. Thus, spinal osteoporosis in men is frequently associated with recognizable risk factors, some of which are potentially remediable.