In response to many anthropogenic pressures on Aby lagoon, the aim of this study is to determine, according to seasons, physicochemical characteristics and nutrients content of lagoon waters. To do this, from September 2007 to July 2009, during monthly sampling campaigns, physico-chemical parameters such as temperature, salinity, conductivity, pH and transparency of waters of lagoon were measured, in situ, at twenty (20) stations distributed along lagoon. Water samples were collected at these stations, at the depth of 0.2 m below the surface, to determine in laboratory levels of dissolved oxygen and nutrients such as orthophosphate, nitrite, nitrate and ammonium, using standard methods. Statistical treatments were performed using XLSTAT 7.5 software. Data processed, using Friedman test, show significant seasonal differences between physico-chemical parameters and nutrients of lagoon waters.