Abstract: Childhood obesity portends risk of adult overweight and obesity and its health consequences. This problem is preventable; unfortunately information on the extent of the problem is scarce in Nigeria. This study aimed at determining the prevalence and factors associated with overweight and obesity among preschool children in Port Harcourt. A cross-sectional study was conducted between September and November, 2010. Two hundred and twenty children in pre-nursery and nursery schools in Port Harcourt were studied. Information were obtained using a self-administered questionnaire filled out by their parents. Heights and weights were measured and BMI calculated, CDC BMI-for-age used for classification of overweight and obesity. Analysis was done using Epi Info 6.04 d. The mean age of the preschoolers was 3.2±1.0 years. The prevalence of overweight and obesity were 15% and 8.6%, respectively. There was no significant sex difference (p = 0.720), viewing television longer than one hour daily was not associated with BMI >85th centile (p = 0.118), while consumption of high fat diet (p = 0.046) and sugar-sweetened drinks (p = 0.000), were associated. Prevalence of overweight and obesity was high among preschoolers in Port Harcourt and was strongly associated with consumption of sugar-sweetened drinks. Mothers in Port Harcourt should be discouraged from giving their children sugar sweetened drinks. More robust studies are needed to confirm findings and identify other risk factors.