Background : In 2000, the US Centers for Disease Control and Prevention (CDC) released a set of growth references that address limitations of the internationally recommended 1977 National Center for Health Statistics (NCHS) references. Aim : This study compares length-for-age Z -scores (LA Z -scores), height-for-age Z -scores (HA Z -scores), and age-specific stunting prevalences of undernourished children using the 1977 NCHS versus the 2000 CDC references. Subjects and methods : Data come from > 2000 children from the Cebu Longitudinal Health and Nutrition Study in the Philippines. Anthropometric data were collected bimonthly from birth to 2 years, at 8.5 and 11.5 years, and at 15 years in girls and 16 years in boys. Z -scores and stunting prevalences are compared between references. Results : LA Z -scores were generally lower using the 1977 references, and stunting prevalences were higher from 0 to 2 years, with some crossover. Differences in HA Z -scores after 8.5 years of age were inconsistent in both direction and magnitude by reference and sex, with additional crossover. Conclusions : When applied to an undernourished population, the two references in question perform differently, with inconsistencies in direction and magnitude of Z -scores and stunting prevalences. The 2000 CDC growth references are clearly an improved tool. However, there are challenges inherent in switching to a new reference that will require the attention of researchers and field workers.