We present a case of a 63-year old man with severe chronic plaque psoriasis and a recent history of lung cancer, wherein fever appeared suddenly after initiation of treatment with low dose acitretin. Tumor recurrence or infection was not found during extensive examinations, nevertheless the patient was empirically treated with broad-spectrum antibiotics without any effect on fever. Immediately after discontinuation of acitretin therapy, the fever disappeared. The patient was followed for next 2 years, during this period similar problems did not reappear, although there has been a relapse of psoriasis and the patient was switched later on biological treatment.