In this book, an analysis is undertaken of the relationships between rainfall variability in the Republic of Congo and atmospheric and oceanic dynamics. Three types of indices are used: rainfall indices (North-Congo Index, Centre-Congo Index, South-Congo Index); oceanic indices: AMO (Atlantic Multi-decadal Oscillation), NAO (North Atlantic Oscillation), SOI (Southern Oscillation Index) and Nino3_4; atmospheric indices (geopotential at 1000 hPa). The evolution of annual and seasonal precipitation shows a significant downward trend since 1980. Parametric and non-parametric tests (Mann-Kendall, Pettitt, Buishand, Hubert) confirm 1970 as the year of break in the precipitation time series. Two major periods stand out: 1950-1970 (wet) and 1971-2005 (dry). The canonical correlations between rainfall indices, oceanic indices and atmospheric indices on an annual and seasonal scale reveal a relatively strong link, materialized by significant correlations.