OBJECTIVE Overweight has been increasing in several developed countries over the last few decades. No update information on the issue is available for Italy. METHODS We conducted a computer assisted personal in-house interview survey in March-April 2004, on a sample of 2932 Italian individuals (1407 men and 1525 women) aged 18 years or over, representative of the general adult Italian population. Information on weight and height was self-reported. RESULTS Overall, 3.4% of the Italian adult population were underweight (< 18.5 kg/m2, 0.9% of men and 5.8% of women), 31.3% were overweight (25.0-29.9 kg/m2, 38.4% of men, 24.7% of women), and 8.2% were obese (> or = 30.0 kg/m2, 7.4% of men and 8.9% of women). Overweight or obesity was reported by 14.2% of subjects aged 18-24 years (20.6% of men and 7.6% of women). The highest proportions of overweight and obese subjects were in the 45-64 year age group for men (51.4% overweight, 10.0% obese) and in the > or = 65 year age group for women (38.8% overweight, 13.8% obese). Age- and sex-standardised prevalence of overweight or obesity was 36.0% for more educated subjects, and 54.0% for less educated ones. It was 32.3% in northern, 44.3% in central and 47.0% in southern Italy. Overweight increased from 1983 to the early 1990s, and levelled off thereafter. Prevalence of obesity remained around 8-9% across the last 20 years. CONCLUSIONS Trends of overweight and obesity in Italy are more favourable than in several developed countries. Still, approximately 15 million of Italian adults are overweight and 4 million obese.