In the current context of economic stabilization in the states of the West African Economic and Monetary Union (WAEMU), and as an extension of the reflections on the factors leading to growth in developing countries, one should examine the role of public expenditure in promoting growth in the WAEMU countries. The aim of this study is to estimate the impact of the level and the composition of public expenditure on growth in the WAEMU countries for the period 1965-2000. Based on the resulting estimates, that in the short term, total public expenditure has no significant impact on growth in most of the countries. In the long term, however, an increase in public expenditure does have an impact on growth, although strongly varied by country. The examination of the composition of the public expenditure revealed the negative effect of public consumption expenditure on growth in both the short and the long term in the Union. However, the impact of public investment expenditure is positive, essentially in long term.