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 anterior-central and the middle-central regions and in the dorsal area of the posterior-central region. On the other hand, those containing probably a 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 α-methyldopa. No DA cells were found in the caudal region