Several acids present in the acidic fraction of boar preputial fluid have been identified by gas chromatography. They are acetic, propionic, n‐butyric, isobutyric, n‐valeric, isovaleric, α‐ and β‐methylvaleric, caproic, n‐nonanoic and n‐undecanoic acids. Unsaturated aliphatic acids include pent‐4‐enoic, pent‐2‐enoic, hept‐2‐enoic and oct‐2‐enoic acids. Benzoic, phenylacetic and β‐phenylpropionic acids were also identified. Several peaks remained unidentified. Quantitative data for the major components (aromatic acids and acetic acid) are presented and also for the C3 to C5 saturated aliphatic acids which are known to have unpleasant odours and low thresholds of detection. The contribution of these compounds to the odour of a boar is discussed, but it is concluded that they contribute little to the taint of heated boar fat. Copyright © 1968 John Wiley & Sons, Ltd