The distribution of the dopamine (DA) cell bodies was elucidated within the mouse arcuate nucleus by fluorescence histochemistry. The arcuate nucleus was divided into five regions; heterogeneity in distribution and different amounts of DA among the regional areas were demonstrated. The DA cell bodies containing a large amount of DA, observable even in the arcuate nucleus of the intact mice, distributed in the medial areas of the anterio-central and the middle-central regions and in the dorsal area of the posterior-central region. On the other hand, those containing probably as small amount of DA distributed in the medial area of the rostral region and in the ventral areas of the anterior-central and middle-central regions. They were not observed in the intact mice, but found in the mice treated with nialamide plus alpha-methyldopa. No DA cells were found in the caudal region.