1967 census data, the provisional results of the 1978 population census and other available population data are used to review the population situation in the United Republic of Tanzania. An attempt is made to examine the size and composition of the population, population growth during the 1967-1978 period, population distribution and density, and fertility and mortality levels and trends. Also an attempt is made to project the population to the year 1975. The results of the 1967 census showed that Tanzania had a total population of about 12,313,469. The population had grown to 17,527,564 by 1978. The population growth rate for mainland Tanzania between 1967-1978 was 3.2% per annum. There are reasons to believe that the growth rate is likely to be too high. It has been suggested that the 1978 census was of better quality than the 1967 census. The underenumeration of the 1967 census, believed to be about 2.5%, was significant. Regional growth rates reveal substantial differences among the regions between 1967-1978. The rapid rate of population growth has the effect of increasing the population under age 15. In 1978 the proportion of this age group was about 46% of the total population. Those in the working group, i.e., 15-64, was about 50%. These proportions have economic implications for meeting the needs of the population under age 15. Tanzania is sparsely populated as revealed from the population density which increased from 14 persons/km2 in 1967 to 29 persons/km2 in 1978. The primary concern in relation to population density should be to relate population size and growth to available resources in Tanzania. Estimates from the 1967 census, the 1973 demographic survey and provisional 1978 census data all indicate that the crude birthrate was about 47/1000. Total fertility estimates were as follows: 1967 census, 6.6; 1973 national demographic survey, 6.3; and 1978 census provisional data 6.5. From a total fertility estimate of 5.6 from the census of 1956, fertility has increased substantially. Mortality appears to have declined based on the crude death rate estimate of 21-23/1000 in 1967 to 18/1000 based on the 1978 provisional data.