Levels of sound intensity were measured over periods of 24 hours in 34 abattoir lairages in England and Wales. The mean integrated range in 12 cattle lairages was 52 to 79 dB(A), in 11 sheep lairages, 45 to 76 dB(A) and in 11 pig lairages, 46 to 87 dB(A). In general, the pig lairages were the noisiest, with spot peak recordings of up to 110 dB(A). Typically, the sound intensities in all the lairages were 10 to 20 dB(A) higher during the working day than at night. In many sheep lairages, high intensities of sound were recorded frequently throughout the night, but others were very quiet, below 40 dB(A). Vocalisations were the major sources of noise in the pig and cattle lairages, but there were variations between them. There were high intensities of sound from handling systems (80 to 90 dB[A]), and ventilating fans (70 to 80 dB[A]).