The aerodynamic bases of articulatory defects which characterize velopharyngeal insufficiency are not yet well defined. The purpose of our investigation has been to establish the type and the severity of aerodynamic alterations correlated with this syndrome before and after logopedic treatment; thus we have exposed the phoneme /p-i:/, produced by 20 control individuals and by 12 patients with velopharyngeal insufficiency, to an aerodynamic study by means of a computerized system (Aerophone II, FJ Electronics) able to record, at the same time, phonatory airflow, intraoral pressure, and sound intensity. The data collected were subjected to statistical analysis by using Student’s t test. The results obtained before logopedic treatment documented: (1) a remarkable articulatory distortion during the implosion of/p/ by a two-phasic pressure wave with a reduced amplitude compared to the one registered in control group subjects (7.3 ± 2.8 cm H2O vs. 10.9 ± 2.7 cm H2O; mean ± SD; p < 0.01); (2) the presence of a nasal airflow in this same phase (0.13 ± 0.07 liters/s); (3) peak airflow relative to the explosion of /p/ inferior to the one recorded in the control group (0.41 ± 0.08 liters/s vs. 0.57 ± 0.11 liters/s; p < 0.01); (4) a mean ratio between the duration of the implosive phase of /p/ and that of the whole articulatory cycle inferior to the value recorded in the control group (34.8 ± 2.6% vs. 39.2 ± 2.3%; p < 0.01). At the end of logopedic treatment the aerodynamic investigation allowed to correlate the improvement of the speech defects due to rehabilitation to precise aerodynamic data: (1) a monophasic pressure wave with a peak (14.9 ± 4.7 cm H2O) that is higher than the one observed in the control group (p < 0.01) and the one observed in patients before therapy (p < 0.01); (2) a significant reduction of the nasal airflow recorded before logopedic treatment (0.04 ± 0.04 liters/s; p < 0.01); (3) a remarkable increase in peak airflow compared to the one recorded before logopedic treatment (0.93 ± 0.25 liters/s; p < 0.01); (4) a further reduction of the mean percentage ratio between the duration of the implosive phase of /p/ and that of the whole articulatory cycle (29.2 ± 2.0%; p < 0.01) as compared to the one recorded before logopedic treatment. The results of our investigation underline how many different aerodynamic factors are involved in the pathogenesis of articulatory defects of speech related to velopharyngeal insufficiency, and how they reciprocally interfere; furthermore, our data indicate that logopedic treatment does not always restore physiologic conditions, but often facilitates the realization of particular articulatory strategies which are not found in norm