The term 'failure to thrive' (FTT) is widely used to describe inadequate growth in early childhood. However, no consensus exists concerning the specific anthropometrical criteria to define this description. The aim of this study was to make an updated assessment concerning the use of FTT definitions and describe possible trends regarding the use of specific criteria. A cross-sectional review was done covering English-language articles published from January 2003 until June 2004, and recent textbooks of general pediatrics. Most of the reviewed literature broadly defined FTT as inadequate growth and total agreement existed to define FTT based solely on anthropometrical parameters. Large differences, however, were seen regarding which growth parameters to use and whether to use attained values or velocities. Weight was the most predominant choice, but many included more than one anthropometrical parameter. Failure to thrive in children is currently described solely based on anthropometrical indicators, with weight gain as the predominant choice of indicator and cut off around the 5th percentile. Discussion is needed as to whether the term 'failure to thrive' is still a useful common term for pediatric undernutrition of different types.