In 1987, the first major dental epidemiological study was carried out in the Kingdom of Saudi Arabia, with the help and cooperation of the WHO Collaborating Centre for Oral Health Services Research, University Dental School, Cork, Ireland. As part of the project, the 15-year-old age group underwent an interview survey in order to ascertain if oral health attitudes and behaviour were related to oral health outcomes, as measured by the mean DMFT for the group. In common with the findings of similar studies in other countries, including Ireland, little or no correlation between the sociological variables and oral health outcomes was apparent. Such findings, however, simply highlight the unreliability of cross-sectional designs when attempting to isolate a relationship between a cumulative condition, such as dental caries, and parameters which clearly change with time. The differences found in the oral health behaviour of the Saudi Arabian and Irish 15-year-old children is particularly noticeable in respect of the frequency of intake of sweet foods and drinks.