Mycoplasma pneumoniae, the major pathogen of primary atypical pneumonia, is reported as the most common infectious agent associated with Stevens–Johnson syndrome (SJS) in children. For that reason it is important to consider mycoplasma infection also in the absence of classical pulmonary symptoms. SJS is a rare and acute, self-limited disease, characterized by severe inflammation and necrosis of two or more mucous membranes. We report the case of a 12-year-old boy with a diagnosis of SJS induced by M. pneumoniae infection. The patient's SJS relapsed 8 months after discharge. When the condition is recurrent, it is important early on to identify the cause of a single episode to optimize care and therapeutic choices.