Surfactants are used in agriculture as soil conditioners and components of fungicides, pesticides, and fertilizers. These materials are considered contaminants found in the soil. They can be absorbed by plants and animals and can impact human health when consumed. The objective of this study was to evaluate the phytotoxicity of four cationic surfactants: hexadecyl trimethyl ammonium bromide (HDTMA), octadecyl trimethyl ammonium chloride amine and amine in a hydroponic culture system of lettuce in doses of 0 to 10 mg/L. The variables evaluated were water consumption, dry biomass, leaf area, electrical conductivity (EC), and content of NO3-, K+, and Ca2+in the nutrient solution. After 40 days of exposure to DDA, this did not influence the dry biomass of the plant; however, the application of 1 mg/L of HDTMA decreased the biomass by 27 %, 46 % with 4 mg/L of OTAC, and 60 % with 4 mg/L of HDA. The decrease in water consumption by surfactants was 27 % with 1 mg/L of HDTMA, 20 % with OTAC, and 34 % with HDA from 2 mg/L, and the application of DDA did not show a reducing effect. In most of the variables, the DDA surfactant did not affect the response; in addition, the HDA surfactant was the second to cause the least damage to the crop because it does not have a toxic companion ion such as Cl and Br.