Biomonitoring programs, such as those being conducted at the Centers for Disease Control and Prevention in conjunction with the National Health and Nutrition Examination Survey (NHANES), are of benefit to all disciplines of environmental public health. However, all programs have limitations, and like most things in science, "One size does not fit all." We point out some of these limitations, particularly those dealing with the amount of biological sample available from various age groups and the specificity of the exposure assessment. We recommend additional studies to supplement the NHANES biomonitoring data.