In situ hybridization was used to assess the subcellular distribution of mRNAs encoding several important neuronal proteins in hippocampal neurons in culture. mRNA encoding GAP-43, a protein that is largely excluded from dendrites, was restricted to nerve cell bodies, as were mRNAs encoding neurofilament-68 and beta-tubulin, which are prominent constituents of dendrites and of axons. In contrast, mRNA encoding MAP-2, a protein that is selectively distributed in dendrites and cell bodies, was present in both dendrites and cell bodies. These results demonstrate that different mRNAs are differentially distributed within individual hippocampal neurons. Taken together with previous findings from other laboratories, our results suggest that only a limited set of mRNAs are available for local translation within dendrites.