Abstract Background and Aim: To evaluate the prevalence of goitre by means of urinary iodine excretion, palpatory and ultrasonographic thyroid examinations in a heterogeneous population living by the sea. Methods and Results: We used a special self-administered questionnaire to evaluate thyroid size, iodine intake, eating habits and cardiovascular risk factors in 600 subjects with a mean age of 45±17 years: 253 men (42.3%) and 347 women (57.7%). Urinary iodine excretion was low (72.1±15.7 μg/L; median 71.2) and associated with ultrasonographic evidence of an enlarged thyroid (16%) or structural thyroid abnormalities (30%), thus allowing us to define the Salerno Gulf as a mild-moderate area of endemic goitre. All of the subjects ate a Mediterranean diet, with a mean of two portions of fish/week. The cardiovascular risk factors considered were obesity, cigarette smoking, hypertension, hypercholesterolemia, hypertriglyceridemia and diabetes, the prevalences of which were in line with those reported in other studies of similar age-matched populations. Conclusions: The moderate intake of fish and the consumption of a Mediterranean diet did not prevent goitre. Iodine deficiency and subsequent goitre endemia are also present at sea level, probably because of a diet based on local products grown on soil with a low iodine content or possible seawater, soil and air environmental pollution that may interfere with the availability of iodine. The assessment of iodine deficiency should therefore involve the entire population and not only subjects living far from the sea.