The purpose of this article, regarding the professional experience of the author and some knowledge on methods and sources, is shows two or three questions on the statistical function in the context of migrations and demographic situation in Portugal, and to present some contributions for consideration on the perspectives of future actions in this matter. In the scope of institutional co-operation between NSI, CESD-Lisbon and ISEGI (Institute of Statistics and Information Management), a training project of which the author was the leader, in the field of migration statistics contributed to the creation of a database on official Portuguese emigration, during the period 1960 to 1988. From this positive experience, some references, related with the subject, have been appearing, concerning facts, constraints and benefits, as well as the dichotomy between the statistical data and the real events, in the permanent search to develop the international migration statistics.

keywords: training project, official and irregular emigration, documented and irregular immigration, migrant flows (inflows or outflows), net migration, population estimates, population census, borders control, household survey, population registers.