Cervico-vaginal mucus was collected from 140 cows at or near estrus. Samples were partially purified, evaporated, and reconstituted in water for testing over a 2-year period to determine if any extracts would sexually excite bulls. Extracts warmed to body temperature were randomly presented in a flat dish to bulls that were loosely confined in a stanchion, with no cows around. Certain types of extracts evoked linked behaviors comparable to those exhibited naturally with estrus females (olfactory inspection, licking of sample, flehmcn, penile contraction, preputial secretion). Extracts were also examined by gas chromatography - mass spectrometry. Analysis identified over 20 compounds: alcohols, diols, alkenes, ethers, diethers, ketones, primary amines, aromatic alkanes. Nine compounds were found in samples that had been validated as being sexually stimulating; six of these were validated as positive with another bull when randomly tested after 1 year of storage. None of these compounds to our knowledge has been reported as present in estrous mucus and one or more of them may be considered as putative sex pheromones. © 1987 IRL Press Ltd.