BACKGROUND Fever of unknown origin is a complex problem in dialysis patients with recently rejected renal allografts, due to the contribution of the newly withheld immunosuppressive agents to the immunosuppression of uremia, resulting in an atypical presentation of infections, a main cause of fever in these cases. METHODS Two dialysis patients with recently rejected renal allografts who were hospitalized because of fever of unknown origin are reported. Biochemical, bacteriological and imaging studies were performed for specific diagnosis. RESULTS Extensive laboratory investigations failed to yield any diagnosis and allograft nephrectomy was performed in one patient, with a probable diagnosis of inflammation of the allograft, which resulted in no improvement. Eventually, both patients were found to have adrenal insufficiency responsible for the fever, which improved after steroid replacement. CONCLUSIONS Adrenal insufficiency should be suspected in all dialysis patients presenting with fever and atypical symptoms, but only after other potential causes are eliminated; since steroid administration may normalize fever regardless of the etiology, it may mask the signs and symptoms and delay the treatment of other (if any) underlying disorder(s).