Objective: To develop predictive equations for respiratory muscle strength (RMS) in 5 to 10 year old children. Materials and methods: This was a cross-sectional study in which 148 children took part, including boys and girls between 5 and 10 years of age. They were evaluated using a respiratory disease questionnaire validated for Brazil, and then submitted to a spirometric and anthropometric evaluation. The RMS measurements were obtained by manovacuometry and consisted of the maximum respiratory pressures. All the evaluations were carried out on the same day by the same evaluator. Results: The predictive power of the equations (R2) was between 25 and 63%, and by applying Pearson's correlation test it was shown that the MIP and MEP of the boys and girls presented significant correlation with age, height and body mass. Thus the mathematical models were separated according to gender and the results submitted to multiple linear regression. A Bland-Altman visual analysis was also used to evaluate agreement between the proposed predictive values and those of other already existing MIP and MEP equations. Conclusion: The equations giving predictive values for the MIP and MEP in 5 to 10 year old children were shown to be reproducible.