In an attempt to shed light on aid effectiveness in LDCs, this paper aims to study possible causality relations between economic growth per capita and official development assistance (ODA) flows. A second objective of this paper is to test for potential causality relations between openness to trade and economic growth per capita in LDCs; which is, again, an important issue for policy purposes since all successive UN PoAs commonly foresaw trade liberalization, in itself, as a means to enhance economic growth in this group of countries.