A growing body of evidence indicate that bone marrow participates in the pathogenesis of rheumatoid arthritis (RA). We and others have shown that in bone marrow of RA patients inflammatory response can develop. In addition, pathological events in bone marrow may even precede the signs of synovitis. Furthermore, the association of bone marrow lesions in RA with more erosive disease was found. Published few months ago two reports provided some evidences that support concept of a key role of bone marrow in ACPA-positive RA as a site where bone destruction can be initiated. These new data identify also ACPA as osteoclastogenesis promoting factor. The results of recent studies may thus bring us closer to the understanding of mechanisms triggering pathological events in RA and suggest new potential targets for therapeutic and preventive interventions interfering with osteoclasts activity.