Purpose: Electroretinography (ERG) is frequently a relevant diagnostic test in pediatric ophthalmology and neurology. ERG at early age is not easy to perform and requires simplified recording protocols and specific norms. In our laboratory especially devoted to developmental studies, an ERG recording method has been adapted to the very young infant. Methods: Monocular ERG was performed in 60 healthy subjects from birth at term to 3 years of age. ERG was recorded using disposable contact lens electrodes in the conscious child with eyes open, after topical anesthesia but without sedation. Stimulus was a white flash (color temperature 5600°K, energy at source 0.3J) applied in a room with a background light of 0.55lux. Analysis was focused on the amplitudes and latencies of the a- and b- waves, and the presence of oscillatory potentials (OP). Results: Values of a- and b- waves amplitudes (in microvolts ± SD) and a/b amplitude ratio were: from birth to 90 days: 33.7 ± 11.1 µV (a), 141.7 ± 40.3 (b), and 0.25 ± 0.09 (a/b); from 91 to 180 days: 55.9 ± 14.0 (a), 233.1 ± 58.2 (b), and 0.25 ± 0.06 (a/b); from 181 to 365 days: 60.3 ± 19.4 (a), 294.5 ± 92.6 (b), and 0.21 ± 0.06 (a/b); from 1 to 3 years: 74.6 ± 21.1 (a), 338.0 ± 76.6 (b), and 0.23 ± 0.06 (a/b).Latencies (in milliseconds ± SD) were: from birth to 90 days: 20.2 ± 1.9 (a), 58.1 ± 6.7 (b); from 91 to 180 days: 18.1 ± 2.0 (a), 48.5 ± 6.1 (b); from 181 to 365 days: 19.2 ± 2.1 (a), 47.2 ± 2.9 (b); from 1 to 3 years: 19.6 ± 1.9 (a), 43.5 ± 2.3 (b).Before 3 months, either no OP was seen or only OP2. After 1 year of age, OP2 was always present, associated with OP1 or OP3 on two third of the subjects. Conclusions: The mesopic ERG is a mixed rod-cone response recordable within a short investigating session using a protocol suitable for the very young. This test can be routinely used to evaluate the functional maturation of the retina from birth onwards.