To examine the prevalence and trends in excess weight among children in the Seychelles. Serial surveys of weight and height were conducted each year between 1998-2002 in all students attending four school grades (crèche, 4 ^th , 7 ^th and 10 ^th years of compulsory school). Overweight and obesity were defined using age-specific body mass index (BMI) criteria of the International Obesity Task Force. Two questions explored physical activity at leisure time and daily walking time. From an eligible total of 32 077 observations between 1998-2002, data were available in 22 694 (71%), which corresponded to 17 627 separate children. Median age in the four grades was respectively 5.5, 9.2, 12.6, and 15.8 years. The overall prevalence of excess weight ('overweight' and 'obese' categories combined) was 10.5% in boys and 16.4% in girls. From 1998 to 2002, the prevalence of excess weight increased from 8.4% to 11.8% in boys and from 11.9% to 18.4% in girls. The increase of excess weight over calendar years was particularly marked among the younger children. Only a quarter of children reported walking at least 30minutes per day. Leisure physical activity was inversely associated with excess body weight. The prevalence of excess body weight was high among school children of Seychelles and increased substantially over a five-year period. This calls for prompt and energetic policies and programs to promote physical activity and healthy nutrition among children.