1. The development of the ERG of the pigmented Dutch Belted rabbits is completed before the age of 5 weeks. 2. The a-wave amplitude attains the adult value by the age of 40 days. 3. The b-wave amplitude development is fastest before the age of 40 days but continues to increase afterwards probably due to increase of eye size. 4. Both a- and b-wave peak-latencies decrease with increasing age to the age of 40 days. 5. The b-wave seems to originate from two processes, one leading to a "slow b-wave" showing low threshold, long peak-latency and in adult animals no oscillatory potentials, which dominates the low stimulus intensity response. The other, a "fast b-wave" of higher threshold, shorter latency, and showing oscillatory potentials, dominates the high stimulus intensity response. 6. Light deprivation does not retard the early development of the ERG in rabbits.