A four-point photographic scale was developed to score the severity of lesions of footpad dermatitis (FPD) in broiler chickens. There was a linear relationship between the square root of the relative area of the lesions and their scores, and good agreement between different assessors using the scale. The scale was used to assess samples of 100 birds from each of 190 flocks slaughtered at two UK processing plants in 2002 and 2003; 12 of the flocks (6·3 per cent) had no lesions, but the others had lesions of different prevalences and severity. The maximum proportion of affected birds in a flock was 92 per cent. In the 178 affected flocks, 84·0 per cent of the birds had no lesions and 16·0 per cent had some evidence of FPD. The overall unweighted prevalence of birds with FPD in all 190 flocks sampled was 18·1 per cent; 10·2 per cent had only small lesions, on average equivalent in area to 2·1 per cent of the total area of the foot, 6·2 per cent had lesions on average equivalent to 6·6 per cent of the area of the foot, and 1·7 per cent had lesions on average equivalent to 21·5 per cent of the area of the foot. There were differences between the two plants in the overall prevalence and severity of FPD, but this may have been due to the fact that the plants were sampled at different times of the year.