Four Cleaning-In-Place (CIP) methods for dairies were compared using life cycle assessment (LCA). The methods were conventional alkaline/acid cleaning with hot water disinfection, one-phase alkaline cleaning with acid chemical disinfection, enzyme-based cleaning with acid chemical disinfection and the conventional method with disinfection by cold nitric acid at pH 2. Production of detergents, transport, the user phase in the dairy and waste management of containers were included. The user phase was found to be the most important part of the life cycle. The CIP methods with small volumes and low temperatures, such as enzyme-based cleaning and one-phase alkaline cleaning, turned out to be the best alternatives for the impact categories energy use, global warming, acidification, eutrophication and photo-oxidant formation. Milk residues flushed out in the rinsing phase were the main contributor to eutrophication, but the phosphorus and nitrogen in the detergents also influenced the results. Evaluation of toxic substances poses a methodological problem in LCA. In this study, detergents partly composed of toxic substances were included, and the overall assessment was that the one-phase alkaline cleaning method was preferable from an environmental point of view. A qualitative assessment of toxicity was performed. © 2003 Published by Elsevier Science Ltd. on behalf of Swiss Society of Food Science and Technology.