Chlamydia pneumoniae is a common cause of acute infections within the upper respiratory tract. It is less well known that chlamydia pneumoniae, just like chlamydia trachomatis, may also trigger reactive arthritis. We describe three patients with arthritis possibly triggered by chlamydia pneumoniae. The patients showed the typical symptoms of reactive arthritis like asymmetric oligo- or polyarthritis, dactylitis, enthesiopathies and tendovaginitis. The course of the disease was quite different. The first patient developed persistent polyarthritis which required longterm treatment with a rheumatic disease modifying drug; the second patient improved after several weeks and the third patient experienced a full remission within a few days.