The effect of drinking water, soil mineral composition and nutrition on the incidence of goitre in Plateau State, Nigeria, was studied. The study shows that the water used for drinking and cooking in the goitrous areas is low in iodine content and trihalomethanes, but high in mineral content, including calcium, magnesium, nitrate, chloride and total hardness. The water is also high in organic, inorganic and bacterial pollution content. Soil pH in the goitrous area is acidic and mineral composition follows the same pattern indicated from water analysis. Soil iodine content is very low. Diet in the goitrous zone consists mostly of foods with high cyanogenic glycoside and low iodide. The ratios of iodide to thiocyanate in urine excreted by subjects from both goitrous and non-goitrous areas show a strong correlation with goitre endemia. These studies exemplify goitre as having multicausal factors--lack/deficiency of iodine, familial or genetic tendencies, diet, and pollutants which serve as goitrogens.