Vision acuity and visual evoked potentials (VEP) to a homogeneous light field and chess field reversion were studied in children aged 5-6 years with unilateral amblyopia before and after 3-month direct total occlusion of the intact eye. Occlusion of the intact eye resulted in improvement of the vision acuity and VEP of the amblyopic eye, that correlated with the degree of amblyopia. At the same time examinations of the intact eyes revealed reduced amplitude of VEP to large and increased latency to small chess pattern cells but no changes of the vision acuity. The results evidence the necessity of monitoring the occlusion by VEP recording to prevent the detrimental effects of visual deprivation on the development of the system of vision in a child.