Unsubstituted as well as α-, β- and (ω-1)-hydroxy substituted fatty acids were analyzed in a 5 m long sediment core taken from Lake Léman (Switzerland). All these acids occur in three forms: unbound, bound and tightly bound and our results show that there is no conversion from one form to another. The fact that below a burial depth of 30 cm the abundance profiles show no decreasing trend indicates that the diagenetic reactions do not operate below that depth. On the basis of our results, compared with other published data, source correlations are postulated for each of the acid classes. The presence of unsubstituted monounsaturated acids in the C₂₀ to C₃₂ range probably indicates that long chain fatty acids cannot be considered only as indicators of inputs from higher plants. Finally, C₂₇, C₂₉ and C₃₁ (ω-1)-hydroxyacids with unusual structures have also been found in these sediments, as well as 2-methyl nonacosanoic acid; their origin has not yet been established.