The combination of acute urinary retention and aseptic meningitis has not been well recognized. This combination can be referred to as meningitis-retention syndrome (MRS), when accompanied by no other abnormalities. However, the responsible site of lesions for urinary retention in MRS remains obscure, despite the areflexic detrusor at the time of urinary retention. We recently encountered a man with MRS in whom a urodynamic study was performed twice. In that case, an initially areflexic detrusor became overactive after a 4-month period, suggesting an upper motor neuron bladder dysfunction.