BACKGROUND: The prevalence of allergic diseases is increasing worldwide, but the reasons are not well understood. Previous studies suggest that this trend might be associated with lifestyle and urbanization. OBJECTIVE: We sought to describe patterns of sensitization and allergic disease in an unselected agricultural Chinese population. METHODS: The data were derived from a community-based twin study in Anqing, China. Skin prick tests were performed to foods and aeroallergens. Atopy was defined as sensitization to 1 or more allergens. Allergic disease was ascertained by means of self-report. The analysis was stratified by sex and age (children [11-17 years] and adults [>or=18 years]) and included 1059 same-sex twin pairs. RESULTS: Of 2118 subjects, 57.6% were male (n = 1220). Ages ranged from 11 to 71 years, and 43.3% were children (n = 918). Atopy was observed in 47.2% (n = 999) of participants. The most common sensitizing foods were shellfish (16.7%) and peanut (12.3%). The most common sensitizing aeroallergens were dust mite (30.6%) and cockroach (25.2%). Birth order and zygosity had no effect on sensitization rates. Multivariate logistic regression models revealed that risk factors for sensitization include age for foods and sex for aeroallergens. The rates of food allergy and asthma were estimated to be less than 1%. CONCLUSIONS: Atopic sensitization was common in this rural farming Chinese population, particularly to shellfish, peanut, dust mite, and cockroach. The prevalence of allergic disease, in contrast, was quite low.