Data concerning the systematic determination of anionic surfactants (AS) and non-ionic surfactants (NS) over the period 1990-2000 in a single sampling point (Poznan) is reported, as well as data concerning the determination of these surfactants along the whole of the River Warta measured in 1997-1999. The indirect tensammetric method was applied for the determination of non-ionic surfactants, while the MBAS method was applied for the determination of anionic surfactants. The: average concentration of NS over the period 1990-2000 showed a highly increasing tendency, from approximately 25 mug l(-1) to approximately 150 mug l(-1). The average spring-summer concentration of AS over this period fluctuated around the value of 140 mug l(-1), while autumn-winter average concentrations showed a gradual decrease in average concentration over the last five years, from approximately 300 mug l(-1) to approximately 150 mug l(-1).