The authors present scales of reference theoretical values for children and peak expiratory output (V 50 and V 25), as well as FEV1 and vital capacity obtained by flow-volume curves. After a description of the equipment (adaptable to on-the-spot epidemiological studies), the reference population (537 children, male and female, 6-16 years old), and the method of curve applications, the statistical basis for devising the scale was analyzed. Under study were the following topics: assuming an exponential regression model, advantages of the consideration of two reference parameters (age and size), or of one (size), which was the solution adopted finally to construct the scale. The comparison of our work with that described in the literature for groups of children with widely diversified origins points out the differences in certain functional parameters themselves. Thus, the interest of establishing scales for an epidemiological program based on populations with features as close as possible to those of the groups under study is justified.