Balanitis circumscripta plasmacellularis or Zoon's balanitis is an idiopathic, benign condition of the genitalia that mostly presents as a solitary, persistent plaque on the glans of primarily uncircumcised, middle-aged to older men. Its etiology and pathogenesis remains speculative. This article provides an overview of the clinical morphology, microscopic features, differential diagnosis and therapy. Particular attention is paid to histopathologic features. Besides, a case is presented of an uncircumcised man with clinical and histologic features of balanitis circumscripta plasmacellularis who was successfully cured by circumcision. The distinction of this lesion from similar lesions is rather important, and a large group of disorders such as premalignant, infective and other inflammatory penile diseases should be definitely taken into consideration on the differential diagnosis. It seems that circumcision might be the current 'gold standard' for treatment of this disorder.