Acute generalized exanthematous pustulosis (AGEP) is now a well-known clinical entity, characterized by acute onset with associated fever, and numerous non-follicular pin-head sterile pustules on erythematous background. The biopsy evidences subcorneal pustules resembling those of pustular psoriasis. However, polymorphic aspects such as pseudo-erythema multiforme purpuric lesions, and edema are often associated, and with the rapid self-healing course of this impressive pustulosis, allow the differential diagnosis with pustular psoriasis. Most cases of AGEP are drug induced, particularly by antibiotics and mainly beta-lactams. However, a number of other drugs, of which the list is increasing, may be responsible. Few cases are related to other causative factors such as viral infections or ultraviolet radiation.