The World Health Organization (WHO) has recently released a new child growth standard that it recommends for international use. The objective of this study was to demonstrate the differences and the implications of using the WHO child growth standards on Saudi children. The Saudi reference was based on a cross-sectional sample of the population of healthy children and adolescents from birth to 19 years of age. The WHO sample was selected from privileged households in some countries. Percentile construction and smoothing were performed using the lambda, mu, sigma (LMS) methodology in both studies. The data from the WHO study including the 3rd, 5th, 50th, 95th, and 97th percentiles were plotted on the Saudi charts for weight for age, height for age, and weight for height. There are major differences between the 2 studies. Compared with the Saudi charts, the WHO lower percentiles (third and fifth) are shifted upward, whereas the upper percentiles are shifted downward. The use of the WHO standards in Saudi Arabia and possibly in other countries of similar socioeconomic status increases the prevalence of undernutrition, stunting, and wasting, potentially leading to unnecessary referrals, investigations, and parental anxiety. Clear guidelines should be developed by WHO experts to guide clinicians in developing countries in the proper use of the standards not only to determine prevalence but also in the daily clinical assessment of the growth of children. © 2009 Lippincott Williams & Wilkins.