Low-concentration, highly viscous liquid detergents which maintain their degree of viscosity in storage in a range of climatic conditions, do not undergo any phase separation or agglomerate separation, and maintain their color under the influence of light. Liquid detergents with the desired properties contain 0.2 to 5 wt. % of a polyurethane or modified polyacrylate, 0.5 to 7 wt. % of a boron compound and 1 to 8 wt. % of a complexer.