One surgical option for the treatment of premature sagittal suture synostosis is to excise the ossified sagittal suture and weaken the parietal cranial bones in a minimally invasive procedure during the first months of life. The subsequent head-orthosis therapy is often viewed as disadvantage and its necessity is sometimes doubted. In the case series presented, the postoperative results after minimally invasive surgery with and without subsequent orthosis-therapy was compared.Until 10/2021, orthosis-therapy was not performed routinely in our clinic after minimally invasive surgery for sagittal suture synostoses. From 10/2021 on, head-orthosis was routinely applied after this procedure. Bildren, who were operate < 4 months of age (m) were included in the study. From the first group, children who received standardized 3D-scans pre- and postoperatively were retrospectively evaluated (n=6 from 16). From the other cohort, data from children who had completed helmet therapy after minimally invasive surgery were collected (n=7 from 22). 3D-scans of children without synostosis or plagiocephaly (n=25) served as a control group. Demographic and morphometric data (cephalic index (CI), head circumference, volume; vertex height index (VHI) pre- and postoperatively) were collected pre- and post-operatively (T1=3 to 4 months of age (m), T2=6 to 7 m, T3=10 to 12 m).The preoperative CI (%) was 71±2.21 in the orthesis-group, 72.1±1.75 in the “non-orthesis-group”, and 77.90±1.92 in the control-group. 220.23±29 days postoperatively, the CI was 78.02±1,98 in the orthesis-group and 73.03±1.41 in the non-helmet group (control group: 78.02±0.53). After completion of helmet therapy (T3), the CI in this group was 77.17±1.85 (control group 76.93±0.5), and 68.60±1.40 in the age-matched non-helmet group (pIn the head-orthosis group, the CI normalized postoperatively and remained stable over the examined 12-months-period. The group without consecutive head-orthosis remained below the CI norm. There were no treatment-group differences with regard to head-circumference, the VHI, and volume. Since children who were not treated with a head-orthosis rarely received 3D-scans, the case numbers presented are small. However, the presented preliminary data confirmed the importance of post-operative head-orthosis therapy in the minimally invasive procedures.