14 rats were studied for the nigro-reticular projection. All animals had a relatively large quantity of dextran-fer injected in the middle of the striatum (to label the nigro-striatic cells and to facilitate distinction between the compacta and reticulata zones). 5 days later, HRP was injected in the reticular formation of the ponto-mesencephalic junction (in the ncl. pedunculo-pontinus, pontis oralis et caudalis, and in the caudal parts of the ncl. cuneiformis). Retrogradely labelled nigro-striatic, nigro-reticular and double-labelled nigrostriato-reticular cells were found. In the zona compacta substantiae nigrae, about 1/3 of the total number of labelled cells were identified as nigro-striatic, 1/3 as nigro-reticular, and 1/3 as collateralizing to the striatum and the reticular formation. In the zona reticulata substantiae nigrae, 2/3 of the total number of labelled cells constituted the nigro-reticular and 1/6 the nigro-striatic projections, while 1/6 collateralized to the striatum and the reticular formation. Retrograde HRP transport in the non-collateralized nigro-reticular and in the collateralized nigrostriato-reticular projections originated mainly from the ncl. pedunculo-pontinus and ncl. pontis oralis. Retrograde transport from the ncl. pontis caudalis was much less prominent. The numerous connections projecting from the zona compacta to the reticular formation point to the essentially dopaminergic nature of this projection. Collaterals of the nigro-striatic projection directed towards the reticular formation have not yet been described in the literature available to the author.