A morphometric-statistical analysis was carried out of fifteen hemispheres of thirteen normal brains of human adults. 2. A comparison of the volumes and the cell densities studied in serial sections is only meaningful if the results are corrected for shrinkage, which varies interindividually to a great extent. 3. The mean of the fresh volume of the striatum of the male subjects (10.2 cm3) was 12% higher than that of the female subjects (9.0 cm3), the difference not being significant. The putamen was 13% bigger on the average than the caudate nucleus. The size of the two nuclei was strictly correlated (r = 0.81). 4. The relative volume of the striatum in percent of the hemisphere volume amounted to 1.87% in males and 1.97% in females, of the putamen 0.99% (male) and 1.05% (female), of the caudate nucleus 0.88% and 0.92%, respectively. 5. The mean of the numerical density of small striatal nerve cells (kl. Nz) -- corrected for shrinkage -- came to 1100 kl. Nz/mm3, without evidence of being dependent of sex or age. 6. The corrected numerical density of the large striatal nerve cells (gr. Nz) had a mean of 65 gr. Nz/mm3 with a wide range of 49 to 78 gr. Nz/mm3, without a significant influence of sex or age. 7. The relation of kl. Nz/gr. Nz was on an average of 171:1 with a range of 130:1 to 258:1. 8. The mean of the corrected numerical density of glial cells (Gz) was found to be 41000 Gz/mm3 with a range of 34500 to 49200. Neither a difference between sexes nor a dependency of age was found. 9. The glia index (Gz/Nz) showed a mean of 37:1 with a range of 3.2:1 to 4.7:1. 10. The total number of small striatal cells averaged 100 million for males and 105 Million for females; for the large striatal cells the means were 670 thousand (male) and 570 thousand (female). Differences due to sex failed to be significant. 11. The total number of glial cells decreases with age. The mean of 408 million for males exceeded the mean of 380 million for females by 7% but without significance. 12. The volumetric density of nerve cells of males (4.03 Vol.-%) and females (4.14 Vol.-%) differed very little. 13. The mean fresh volume of a single small nerve cell in the striatum was calculated to be about 3600 mum3, ranging from 2600 to 4600 mum3. 14. The striatal nerve cells reached a total volume of 423 mm3 in males and 374 mm3 in females. 15. The mean of the diameter of the nucleus of the small nerve cells was calculated to be 8.64 mum in males and 8.70 mum in females.