The respiratory muscle strength of elite athletes has been assessed only for some competitive sports and different conclusions have been reported. The aim of this study was to evaluate the inspiratory muscle strength in a group of professional soccer players in comparison with a group of sedentary subjects. Maximal Inspiratory Pressure (PImax) was measured both at Functional Residual Capacity (FRC) and at Residual Volume (RV) in 130 subjects: 27 of these were elite soccer players (all males, aged 22 +/- 3 years) and 103 were normal sedentary subjects (77 males and 26 females, aged 44 +/- 19 years). Predictive linear models were produced by a stepwise regression analysis in the whole sample of subjects. Both PImaxFRC and PImaxRV models included female gender and ageing as negative predictors, and Body Mass Index (BMI) as positive predictor of the inspiratory pressures. The model predicting PImaxFRC was slightly more accurate than the model predicting PImaxRV (r-squared: 0.38 vs 0.36, respectively). After adjustment for the variables entered in these models, PImaxFRC and PImaxRV were respectively 1.54 KPa and 1.08 KPa higher in soccer players than in sedentary subjects but this result was statistically significant (p < 0.02) only for PImaxFRC. We conclude that the inspiratory muscle strength is increased in soccer players and PImax measured at FRC seems more sensitive in order to discriminate between subjects with different level of physical activity.