Brain cells are naturally exposed to a variety of trophic factors during development. Basic Fibroblast Growth Factor (bFGF), a protein found in the central nervous system (CNS) enhances both survival and proliferation of several CNS cell lines. Neonatal mice of the CD1 outbred strain were injected intracerebroventricularly (ICV) with bovine bFGF on postnatal days 2, 4, and 7. bFGF, dissolved in 25 microliters of saline, was given in the 1, 5, 25, and 1000 ng doses. Physical traits such as body weight gain, body length, and tail length were recorded from postnatal day (PND) 2 to PND 12. Neurobehavioral development was scored according to a modified Fox's Scale. The ultrasonic vocalization pattern (PND 8), homing performance (PND 10), open-field activity and exploration of a novel object (PND 18) were also assessed. Pups receiving 25 and 1000 ng doses of bFGF showed a slight but significant acceleration in the appearance of some early sensorimotor reflexes, such as weak and tactile stimulation, forelimb placing and grasping, and screen climbing, during the first postnatal weeks. The other responses were less affected or not affected at all. Data are compared with similar systemic exposure of neonatal mice to Nerve Growth Factor (NGF).