Unilateral acute idiopathic maculopathy (UAIM) is a rare distinct entity characterized by acute exudative maculopathy occurring in young persons. The purpose of this case study is to report transient electro-oculogram (EOG) impairment during the acute stage of UAIM. A 16-year-old healthy female with UAIM in the left eye underwent serial visual field, fluorescein angiography, indocyanine green angiography, full-field electroretinogram (ERG), and EOG. Initial visual acuity of the affected left eye was 4/200 with macular subretinal exudates. Indocyanine green angiography disclosed early phase foveal hypocyanescence persisting into late phase along with late phase foci of pinpoint hypocyanescence scattered in the macular and mid-peripheral regions. Standard full-field ERG responses performed 18 days after the onset of symptoms were normal. Standard EOG revealed a marked reduced light-peak to dark-trough amplitude ratio (Arden ratio) of 1.20 left eye (normal >or= 1.7) and a normal ratio of 2.24 right eye. Five weeks later, the left eye improved to 20/50, and the exudative maculopathy resolved with residual irregular foveal hyperpigmentation. Repeat EOG performed 69 days after onset of symptoms showed recovery and normalization of the EOG amplitude ratio of the left eye from 1.20 to 2.54. Transient EOG impairment with a normal full-field ERG may occur during the early stage of UAIM. This finding suggests a more widespread dysfunction of the retinal pigment epithelium in at least some cases of UAIM.