In childhood, Mycoplasma pneumoniae infections usually present as respiratory tract disease. However, extrapulmonary manifestations can be severe but the association with M. pneumoniae might not be considered. Here two adolescents who presented with severe exudative and ulcerative stomatitis accompanied by conjunctivitis and genital erosions are reported on. The skin was unaffected. The diagnosis of an acute M. pneumoniae infection was confirmed by serology and PCR. There are only few reports about this clinical entity and its nomenclature is inconsistent. The denomination 'incomplete Stevens-Johnson syndrome' has been suggested.