OBJECTIVE:To determine the effects of overweight and obesity on plantar pressures generated by pre-school children during gait. METHODS:Dynamic plantar pressure variables were measured for 17 overweight/obese children (age = 4.4 +/- 10.8 years; height = 1.08 +/- 0.1 m; body mass index (BMI) = 18.5 +/- 1.3 kg x m(-2)) and 17 age, gender and height matched non-overweight peers (age = 4.4 +/- 0.7 years, height = 1.06 +/- 0.1 m, BMI = 15.7 +/- 0.7 kg x m(-2)). RESULTS:When walking, the overweight/obese children displayed significantly larger contact areas and generated significantly larger forces on the plantar surface of their total foot, heel, midfoot and forefoot compared to the non-overweight children. Despite generating these higher forces over larger contact areas, the overweight/obese children displayed significantly higher peak pressures, force-time integrals and pressure-time integrals in the midfoot compared to their leaner counterparts. CONCLUSIONS:Although the overweight/obese children displayed greater midfoot contact, this increased contact area was not sufficient to compensate for the high forces generated during walking, resulting in them experiencing higher midfoot plantar pressures relative to the non-overweight children. The overweight/obese children also experienced significantly higher force-time and pressure-time integrals than their leaner counterparts, suggesting that their midfoot may be exposed to increased stress and, in turn, vulnerable to bony fatigue and soft tissue damage. The impact of these greater plantar pressure variables on foot discomfort and physical activity levels of these young overweight/obese children as they develop into adults requires further investigation.