A 43-year-old woman presented with a generalized febrile illness, an exanthema with mixed maculopapulous and pustulous eruptions on the lower halves of the extremities, elbows, knees, palms and soles. There was also severe arthralgia and asymmetric arthritis. The diagnosis was rat bite fever. The disease became manifest eight days after she was bitten by a pet rat. Rat bite fever can easily be missed, even after adequate anamnesis and physical examination, while the differential diagnostic considerations are numerous. Our patient was cured completely after intravenous administration of penicillin G. Antimicrobial therapy was completed by an oral course of doxycycline.