Goitre is endemic in many parts of Iran. This study was undertaken first to obtain the base line data and identify the nature of the problem and then to take measures to ameliorate it. Shahryar, an endemic area near the capital city, was selected as the pilot field. The sample size was 368 families. Sixty-six per cent of females and 54 per cent of males were goitrous. A food consumption survey revealed that 38 per cent and 62 per cent of the families had failed to receive at least 80 per cent of their requirement for energy and vitamin A, respectively. Free T4 index was normal but significantly lower in grade 2 goitre than the non-goitrous subjects (P less than 0.01). Significant reverse correlations were found between goitre prevalence and vitamin A and protein intakes (P less than 0.05). Supplementation with 40 micrograms iodine/g salt raised urinary iodine excretion significantly (P less than 0.001). We conclude that although iodine deficiency plays the key role in goitre, the association of other dietary factors observed in this study needs further consideration.