Background and Aims Childhood obesity as a global health problem is associated with increased risk of mortality and morbidity. A few studies are focused on prevalence of children obesity based on new WHO growth standards in Iran. The aim of this study was to determine prevalence of overweight and obesity in children attending health centers based on new world health organization growth standards.

Methods In a descriptive study 1035 children aged 24–60 months, attending urban public health centers for receiving routine children health care were surveyed in 2009. Interview with mothers, filling a questionnaire by trained questioner were used for data collection. Soft ware of WHO for PL (WHO Anthro beta version, 17 February 2006) used for data analysis after entrancing data in SPSS software. Overweight and obesity was defined based on Body Mass Index/age above +2SD and +3SD of median Z score.

Results Overall, 15% of the children were overweight. Highest prevalence of overweight was observed in the 24–35 month age group (19.4%).In different age groups of boys and girls, the prevalence of overweight and obesity was calculated 16.7% and 13.3% respectively. Overall prevalence of obesity was 7.3%. Highest prevalence of obesity in the 24–35 month age group (10.4%) was observed. Prevalence of obesity in boys and girls was 9% and 5.6% respectively.

Conclusion Overweight and obesity in 2–5 years children has reached alarming proportion in Ahwaz. Urgent interventional health programs are needed to prevent childhood obesity.