Background Obesity is now an epidemic in most parts of the world.In this cross sectional study,we report the mostrecent data on obesity in Hong Kong Chinese working population and compare the changes over 10 years.Methods Between July 2000 and March 2002,5882 adult subjects from the working class in Hong Kong were recruited(2716 men (46.2%) and 3166 women (53.8%)).They were randomly selected using computer generated codesaccording to the distribution of occupational groups.Results of this study were compared with the data collected from aprevalence survey for cardiovascular risk factors in a Hong Kong Chinese working population conducted in 1990 (1513subjects,910 men (60.1%) and 603 women (39.9%)).Results Standardized percentages of overweight,obesity,and central obesity,in Hong Kong Chinese workingpopulation were 59.7%,35.0%,26.7% in men and 32.0%,21.7%,26.7% in women.Compared to the data collected in1990,the percentage of obesity increased by 5% in men and reduced by 6% in women.The percentage of centralobesity doubled in men (from 12.2% to 26.7%) but remained stable in women.Conclusions There is a doubling of the percentage of central obesity in Hong Kong Chinese working men overprevious decade.Education and proper lifestyle modification program to tackle this social health issue are urgentlyindicated.Chin Med J 2007;120(13):1151-1154 Background Obesity is now an epidemic in most parts of the world. This cross sectional study, we report the mostrecent data on obesity in Hong Kong Chinese working population and compare the changes over 10 years. Methods Between July 2000 and March 2002,5882 adult subjects were from working class in Hong Kong were recruited (2716 men (46.2%) and 3166 women (53.8%)). They were randomly selected using computer generated codesaccording to the distribution of occupational groups. Results of this study were compared with the data collected from aprevalence survey for cardiovascular risk factors in a Hong Kong Chinese working population conducted in 1990 (1513subjects, 910 men (60.1%) and 603 women (39.9%)). Results Standardized percentages of overweight, obesity, and central obesity, in Hong The percentage of obesity increased by 5% in men and reduced by 6% in women was 59.7%, 35.0%, 26.7% in men and 32.0%, 21.7%, 26.7% in women. Compared to the data collected in1990, the percentage of obesity increased by 5% in men and reduced by 6% in women The percentage of centralobesity doubled in men (from 12.2% to 26.7%) but remained stable in women.Conclusions There is a doubling of the percentage of central obesity in Hong Kong Chinese working men over previous years. Education and proper lifestyle modification program to tackle this social health issue are urgently resolved. Chin Med J 2007; 120 (13): 1151-1154