Brain-derived neurotrophic factor (BDNF) is implicated in the control of hippocampal development. In this study, we have analyzed the developmental expression of BDNF mRNA/protein and its receptor tyrosine protein kinase receptor (trk) B mRNA in the mouse hippocampus by competitive reverse transcription/polymerase chain reaction and enzyme-linked immunoassay. Cell-type specificity of BDNF/trkB expression was studied in primary hippocampal cultures. BDNF levels increased stepwise from embryonic day 15 until the second postnatal week, whereas trkB expression was stable throughout development. Neurons and astrocytes expressed both BDNF and trkB. Our data suggest that developmental BDNF action mainly occurs postnatally and indicates that hippocampal neurons and astroglia not only produce BDNF but also appear to be targets for BDNF.