Six types of neurons were identified and characterized by the Golgi technique in the hypothalamic arcuate nucleus of the rat: non-ramified unipolar, ramified unipolar, non-ramified bipolar, ramified bipolar, small multipolar, and large multipolar. All had few spines, both somatic and dendritic spines. Characterization of the neuronal cytoarchitecture of the arcuate nucleus could be useful in developmental studies under specific experimental conditions.