OBJECTIVE: To assess whether the activity pattern differs between normal weight and overweight boys across weekdays and weekend days. METHODS: Physical activity was recorded every 2 s by accelerometry in 32 normal weight and 15 overweight boys aged 8-10 years for four weekdays and two weekend days (South-West England 2007). Summary activity measures and activity pattern characteristics (frequency, intensity and duration of > or =4 s (short) and > or =5-min (long) bouts of > or =light, > or =moderate, > or =vigorous, and > or =hard activity) were recorded. RESULTS: Normal weight boys accumulated more > or =hard activity (p or =moderate long bouts were shorter and less frequent (p or =light, > or =moderate (and for overweight boys > or =vigorous) short bouts dropped-off) (p or =moderate bouts, relative to normal weight boys suggesting that the activity pattern may be important for weight control.