In this prospective analysis of the natural history of osteoarthritis (OA) of the hand, the incidence and progression of various radiographic features of OA were examined in 177 men who participated in the Baltimore Longitudinal Study of Aging. Subjects who were less than 60 years old were selected based on the availability of at least 4 hand radiographs taken during at least 20 years of followup, while subjects who were age 60 or older were required to have had at least 4 hand radiographs taken during only 14 years of followup. Individual joints of the hands were graded for the presence and severity of 5 features of OA: osteophytes, joint space narrowing, subchondral sclerosis, lateral deformity, and cortical collapse. They were also graded according to the global Kellgren/Lawrence scale. The incidence and rate of progression of OA, as measured by all scales, increased in progressively older age groups. Cox's proportional hazards models showed that isolated doubtful osteophytes (Kellgren/Lawrence grade 1) and isolated joint space narrowing predicted the development of the radiographic features of OA. The rate of OA progression slowed as the severity increased. We conclude that, in men, the incidence of radiographic features of hand OA increases with age. Regardless of age, the earliest radiographic signs of OA are joint space narrowing and doubtful osteophytes.