This paper updates a previous review published in 1993. It surveys new data and recently published findings, e.g. promising modern packaging materials such as polyethylene terephthalate (PET) which are attractive to the consumer. After a brief theoretical outline of the mechanisms of the photo-oxidation of foodstuffs, in particular the combined effects (synergy) of light and oxygen, and the key role played by riboflavin as a sensitiser, the review surveys the principal effects of photo-oxidation on dairy products: loss of vitamins, oxidation of unsaturated lipids, discolouration and formation of off-flavour. In the conclusion, this paper proposes a number of simple and concrete measures for limiting or even preventing these reactions by choosing i) the light source, ii) the transmittance and oxygen permeability of packaging materials and iii) the storage conditions