We report a case of unusual extraintestinal yersiniosis in a 16-year-old girl with generalized microinfarctions of the bone and spleen. For the past 2 years she had been repeatedly admitted to our hospital with reactive arthritis, erythema nodosum and iridocyclitis of unknown aetiology. Ultrasound showed multiple round hypoechoic lesions in the spleen that were shown to have low T2 signal on MRI. MRI also showed disseminated nodular lesions of the skeleton that were low T1 and high T2 signal and demonstrated inhomogeneous contrast enhancement. The patient is currently in good health on low-dose nonsteroidal immunosuppressive therapy. This is a unique case of microinfarctions of the skeleton and spleen caused by a severe postinfectious autoimmune reaction following extraintestinal Yersinia enterocolitica infection.