Respiratory disorders are more likely in children with Autism Spectrum Disorder (ASD), Attention-deficit/hyperactivity disorder (ADHD) and Down syndrome compared to the general population. Children with specific disorders or syndrome often experience bronchitis, bronchial asthma, bronchiectasis, and comorbidity, such as cystic fibrosis. The purpose of this research was to evaluate respiratory physiotherapy techniques f or children aged 7-14 years with autism, Down Syndrome, ADHD, and ASDA. Five months of interventions took place in 90 children with ASD, Down Syndrome, ADHD and ADHD/AS D in order to show the beneficial contribution of respiratory physiotherapy. The 90 children were placed in an intervention group (n = 54) and a control group (v = 34). The mean age of the sample was 10.8 years (s.d= 2.3). The intervention program took place three days a week for 5 m onths. Every m onth, (1) Somatometric Stability Testing, (2) Oximetry Testing and (3) Spirometer Testing were recorded. The results showed that both spirometry and oximetry produced significant improvement of the children in the intervention group compared to the control group. A detailed analysis of oximetry measurements showed that the intervention brought a significant improvement in saturation and pulses in the group of children with ASD (p <0.05), ADHD (p <0.05), ASD / ADHD (p <0.05) and Down syndrome (p <0.05). Similarly, the intervention was observed to significantly improve FVC, FVC / pred, FEV1, PEF, PEF / Pred and FEF2575 in the group of children with AS D (p <0.05), ADHD (p <0.05), ASD / ADHD (p <0.05) and Down syndrome (p <0.05). The evidence that emerges from the findings of this research is a strong incentive to continue the effort of investigating the usefulness of respiratory physiotherapy in children suffering from Down Syndrome, ADHD, ASDA.