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The fresh volumes of the nucl. caudatus (including the nucl. accumbens septi), putamen, globus pallidus and of the whole brain of 37 male Tupaia belangeri aged between 36-536 days of ontogenesis have been determined. The growth of these nuclear regions is described by the logistic function. The parameters were approximated by means of an iterative procedure by the least square method. The "ideal" volume of the globus pallidus is 9,6 mm3, of the striatum 113 mm3, and of the whole brain 3 260 mm3. The degrees of maturity of globus pallidus, striatum and the whole brain do not differ significantly from each other concerning the date of birth (43th day of ontogenesis), the growth factors are about 5,5. The nucl. caudatus, including the nucl. accumbens septi, and the putamen demonstrate almost the same course in their degrees of maturity and growth dynamics within the tested age interval. In the course of postnatal development the globus pallidus grows more quickly than the whole brain, and the whole brain, on the other hand, more quickly than the striatum. The half value time of the globus pallidus is about 53 days of ontogenesis, of the whole brain about 56 days of ontogenesis and of the striatum about 58 days of ontogenesis. On the 70th day of ontogenesis, the difference between the degrees of maturity of globus pallidus (93 per cent) and striatum (= nucl. caudatus + nucl. accumbens septi + putamen) (72 per cent) is 21 percent. This complicated growth dynamics can be seen exactly by considering the non-linear logistic functions, the degrees of maturity, and the growth-rate of the degrees of maturity.