Current measurements of 1- and 4-month duration from May 1979 taken at 10 stations in the lower St. Lawrence estuary were subject to time series analysis. We find that the spectral energy density of the near-surface current in the sub-inertial frequency range is comparable to the energy concentrated in the semi-diurnal frequency band. The strong residual current decreases rapidly with depth while the tidal current is more or less uniform from surface to bottom. A cross-spectral analysis showed that the longshore current at a station near the south shore was negatively correlated to the current at a north shore station with high coherence in the period range greater than 7 days. Evidence was found for the existence of a cross-channel current at stations in the center of the channel. The near-surface circulation system in the area can be classified into three types of patterns: (1) one anticyclonic eddy centered between the estuary-gulf boundary and the Baie-Comeau cross-section (region I) accompanied by a cyclonic eddy located to the landward between the two cross sections at Baie-Comeau and Pointe-au-P¿re (region II). (2) a cyclonic eddy in region I with an anti-cyclonic eddy in region II, and (3) the transition phase between phases 1 and 2. The intensity of these eddies and cross-channel currents is related to sea level changes in the estuary.