The accelerating pace of population growth in the turning of the century is the result of a strong and positive net migration.
The low fertility, the increase of expectancy of life, more rapid among men, and the substantial immigratory flux are the remarkable aspects of the demographic evolution in Portugal.
The fall in the number of marriages and the rise in both the number of wedlock births and the number of divorces confirm the new familiar models in Portugal.
The aim is to study the patterns of demographic variables responsible for the major changes in both population size and age structure of the population and culminating in its significant ageing.

keywords: fertility, expectancy of life, migrations, ageing