The objective of this study was to determine whether the ruminal disappearance rate of aflatoxin B1 (AFB1), ochratoxin A (OTA) and fumonisin B1 (FB1) is affected by acidic rumen pH conditions. Disappearance was measured using a temporally isolated rumen model. A buffered solution containing AFB1, OTA and FB1 at pH 5 or 7 was incubated for up to 2 h in the rumen of three adult rumen-cannulated sheep. The mean pH of the solution during the 2-h incubation in the rumen was 6.8±0.15 and 5.7±0.25 for the neutral and acid conditions, respectively. AFB1 and OTA were readily absorbed in the rumen, particularly at acid pH. The disappearance rates at acid and neutral pH for AFB1 were, respectively, 1.98±0.52 and 1.42±0.57 ng/h (p<0.019) and for OTA they were 0.16±0.10 and 0.06±0.03 ng/h (p<0.058). OTA disappearance from the rumen was followed by a concomitant increase of OTA concentration in plasma throughout the 2-h incubation. In contrast, FB1 was not absorbed in the rumen. In conclusion, acid pH in the rumen increases the absorption of AFB1 and OTA, potentially contributing to an exacerbated toxic risk