Knockout mouse is a valuable model to study biological functions of target genes. When Cre expressing mice are bred with mice containing a loxP-flanked gene, the gene between the loxP sites will be deleted in the offsprings. Scientists at the NIH have generated mNF-H-cre transgenic mouse lines that express Cre recombinase under the control of the promoter of the neurofilament-H gene, which is expressed in the late stage of neuronal maturation. The transgenic mice express cre in neurons (but not astrocytes) with highest expression in the cortex and hippocampus. The mNF-H-cre transgenic mouse line can be used to generate conditional knockout mice with targeted excision of neuron-specific genes during the late stage of mouse development. This mouse model will be useful for the study of neuronal functions of particular genes.