Lactones are widely distributed in foods and beverages. Their presence in the aromas of more than 120 foodstuffs (fruit, meat, dairy products, beverages), and their relative importance as flavour impact compounds are reviewed. Their sensory properties, i.e. odour quality, intensity, tenacity and odour threshold, are presented in relation to their structure (4- and 5-olide, molecular weight, length of the side chain, unsaturation) and chirality. The lactone enantiomers are separated either after derivatization (formation of ester diastereoisomers, e.g. Mosher esters) or by direct chiral GC analysis on capillary substituted cyclodextrin columns. Recent data on the relative abundance of R and S enantiomers of lactones present in fruit and dairy products are given. Current knowledge on the biosynthesis and chirality of natural lactones and their link with the lipid metabolism are discussed. Oxo- and the corresponding reduced compounds, i.e. hydroxy fatty acids are likely precursors of lactones. The latter would be subsequently generated from the former through a shortening or, on the contrary, a lengthening of the carbon chain.