UN medium range projections prepared in the 1980 assessment projected the population of individual countries up to the year 2025.  The long range projections discussed here were prepared by projecting the population of 8 major world regions from 2025-2100.  The purpose of the projection was to observe the implications of the changes from the 1978 assessment made in the 1980 medium range projections on the long range projections of the world's populations.  As in previous projections, high, medium, and low variants were prepared in which fertility is assumed to be constant at the replacement level but at different times in the future.  In addition, these projections contain 2 variants not previously prepared--namely, the growth and decline variants, in which the ultimate net reproduction rate is 1.05 and 0.95, respectively.  In all the variants, expectation of life at birth is assumed to reach 75 years for males and 80 for females.  According to the current medium variant projection, the earth's population will become stationary after 2095 at 10.2 billion persons, compared with a total of 10.5 billion projected in the 1978 assessment.  The lower projection is largely attributable to a recent decline in the growth rate of several countries in South Asia which was greater than previously assumed.  When the world population becomes stationary, both crude birth and death rates would be about 13/1000.  In the decline variant, total population would peak at 7.7 billion in 2055, then decline gradually to 7.2 billion in 2100.  The total population as projected by the growth variant would equal 14.9 billion in 2100 and would still be growing slowly.  Between 1980 and 2050, 95% of the world's growth will occur in the currently less developed regions.  Their share of total population will increase from 75-85% during that period.  The age structure in all regions is expected to converge to 1 in which the median age is 39 years, the proportion both below age 15 and above age 64 is about 19% each, and the dependency ratio is about 60.  A precise degree of accuracy cannot be specified, but the argument is made that the actual future population of the world is very likely to fall within the range of the projection variants and probably not far from the medium variant.