We developed methods to assess and to score progression of osteoarthritis (OA) of the distal and proximal interphalangeal (DIP and PIP) and metacarpophalangeal (MCP) finger joints. Thirty-six patients with osteoarthritis (OA) of the finger joints were followed for five years. Anteroposterior radiographs of the hands were obtained at the start of this prospective study and at yearly intervals. The scoring systems used were based on: -1- the increase in incidence of OA during consecutive years in previously normal joints. -2- the radiological progression of the anatomical lesions (changes in osteophyte growth, loss of joint space, subchondral cysts or sclerosis) in pathological finger joints. -3- the consecutive pathological phases recognized in the course of the disease. Significant increases in both the numbers of affected DIP, PIP and MCP joints per subject and the anatomical progression of the disease in the different finger joints of each individual patient were recorded during the 5-year follow-up. In approx. 40% of the patients the classical picture of OA was complicated by manifest erosive changes, which preceded a period in which repair phenomena in the 'eroded' finger joints led to generation of a new subchondral plate covered by cartilaginous tissue. Huge osteophytes were then responsible for the nodular aspect of the affected finger joints. OA of the finger joints in our patients was progressive in nature and went through predictable phases. Recognition and scoring of these phases allowed faster assessment of OA progression and led to the same conclusions as scoring the anatomical progression.