The authors describe a case of Guillain-Barré syndrome and a case of encephalitis, both with serological proven Mycoplasma pneumoniae infection. In the patient with Guillain-Barré syndrome, a 49 year old male who had neurological sequelae five months after discharge, a throat swab was PCR positive for M pneumonia. The patient with encephalitis was discharged 19 days after admission without sequelae.