This review is concerned with the summary and evaluation of the results from more than 150 investigations comparing the quality of conventionally and organically produced food or of foods produced with the aid of di †erent fertilisation systems. Cereals, potatoes, vegetables, fruits, wine, beer, bread, cakes and pastries, milk, meat, eggs and honey, as well as products made from them, have been included in the review. Most of the studies evaluated are physicochemical investigations of concentrations of desirable and undesirable ingredients, pesticide residues, contaminants, sensory analyses and feed experiments with animals. Nutritional studies in humans and experiments which used holistic methods of analysis are also included. Since di †erent methods of sampling were used in the investigations, a summary evaluation of individual results is extremely difficult. Even when the sampling methods are of the same type, a great many factors have to be taken into consideration which are not directly related to the production system but which do inÑuence food quality to a large degree. Despite the heterogeneity of the sample material, some di †erences in quality between products from conventional and organic farming or foods produced with the aid of di †erent fertilisation systems have been identiÐed.