A postal questionnaire was sent to the managers of 857 broiler farms in the UK to determine the prevalence and risk factors for wet litter. The response rate was 75 per cent. Wet litter was reported by 75 per cent (95 per cent confidence interval [CI] 71·3 to 78·3) of the respondents in at least one flock during the year 2001 and 56·1 per cent (95 per cent CI 52·0 to 60·0) of them reported that they had an outbreak of wet litter in their most recently reared flock. Wet litter occurred more often during the winter months and farms using side ventilation systems were at an increased risk (odds ratio 1·74; 95 per cent CI 1·09 to 2·76). A multivariable analysis was carried out using two different definitions of wet litter as outcome variables – all cases of wet litter, and cases of wet litter associated with disease. Consistent risk factors for both outcomes were coccidiosis, feed equipment failures and the availability of separate farm clothing for each house. Cases of wet litter associated with disease were reported by 33·7 per cent (95 per cent CI 28·8 to 39·1) of the managers in their last flock and were associated with the use of hand sanitisers and broiler houses with walls made of concrete.