In structural brain development eight interrelated but distinguishable events can be recognized: (1) neuronal induction, (2) neuroblast proliferation, (3) neuronal migration, (4) neuronal selective aggregation, (5) neuronal differentiation and formation of specific patterns of connection, (6) neuronal death, (7) selective synapse elimination and (8) myelination. The basic mechanisms regulating these developmental events are genetically determined but at any stage of development epigenetic and environmental factors modulate the genetic regulation. This paper reviews representative samples of work in animal experiments and knowledge in human fetal brain development by several authors.