We investigated prevalence and determinants of asthma and allergic diseases in a cross-sectional survey of schoolchildren aged 6-14 in 2002. This was the third of a series of cross-sectional surveys, conducted in 1992 and 1997, in the same school in Ankara, Turkey. Questionnaire including information on house characteristics, dietary habits, past and current exposures and diseases were distributed to 1064 children (523 boys, 541 girls) and filled by the parents at home. Percentage of children having a pet was significantly higher (1992: 7.9, 1997: 22.9, 2002: 21), but that of passive smoking was significantly lower (1992: 74, 1997: 64, 2002: 64.1) in 1997 and 2002 when compared with 1992. Current prevalence percentage of asthma (1992: 8.3, 1997: 9.8, 2002: 6.4), wheeze (1992: 11.9, 1997: 13.3, 2002: 6.4), hay fever (1992: 15.4, 1997: 14.1, 2002: 7.2), and eczema (1992: 4, 1997: 4.3, 2002: 1.8) were significantly lower in 2002 compared with 1992. Multiple logistic regression analysis model for current wheeze included ingestion of cow's milk (no regular ingestion: reference, ORs and 95% CIs, <1 glass/day: 0.5, 0.3-1.0; at least 1 glass/day: 0.3, 0.2-0.7), ingestion of red meat (2.2, 1.2-3.8), and currently holding a dog (6.1, 1.6-23.4). Multiple logistic regression analysis model for current hay fever included ingestion of red meat (1.8, 1.1-2.9) and father's education (none of the parents finished secondary school: reference, secondary school to university: 0.5, 0.2-1.0). Our findings suggested that current prevalence of asthma and allergic diseases decreased among schoolchildren in Ankara, in the last 10 yr, and ingestion of milk and red meat could have a role in the occurrence of asthma and hay fever. Detailed assessment of dietary habits is required to test this hypothesis.