Predicting fat androstenone content using a rapid and cheap method applied to live pigs is needed for efficient genetic selection against boar taint. Piétrain x (Large White x Landrace) boars (n = 90) were slaughtered either at 119 ± 4 kg live weight and 168 ± 1 days of age (S1) or at 116 ± 4 kg and 174 ± 1 days (S2). Blood and saliva samples were collected on D0 (S1: 29 days, S2: 35 days before slaughter) and D27 (S1: 2 days, S2: 8 days before slaughter) in order to measure plasma concentrations of oestradiol and testosterone and salivary concentration of oestrone. A backfat sample was collected on live pigs by biopsy on D27 and on carcasses at slaughter. Testes and Cowper glands were weighed at slaughter. Plasma oestradiol and fat androstenone on D27, taken separately, were good predictors of fat androstenone at slaughter (mean R2 between measured and predicted values was 0.48 and 0.43, respectively for each predictor) in S1 pigs. The quality of the prediction decreased between S1 and S2 pigs despite inclusion of salivary oestrone in the equation with oestradiol. To conclude, plasma oestradiol can be considered as a good predictor of fat androstenone at slaughter if the duration between blood collection and slaughter is short.