Aim of study: To evaluate the effectiveness of miniscrew anchorage for intrusion of upper first molars to correct skeletal open bite. Material and Methods: The study had been conducted on a sample of (14) adult patients their age ranged from 17 to 23yrs (mean age 203yrs) All patients had Angle and skeletal Class 1 malocclusion with skeletal anterior open bite features were treated by molar intrusion using miniscrews. The sample was divided into two groups, according to miniscrew implant assembly used. Group I: Consisted of 7 patients. They received 4 miniscrews (two buccal and two palatal). They were implanted bilaterally between maxillary first and second permanent molars buccally and second premolar and first permanent molar palatally. Group II: Consisted of 7 patients. They received only one miniscrew implanted midpalatally between maxillary second premolars and first permanent molars. A transpalatal arch was used to maintain the molars on each side in order to avoid over rotation during intrusion in group II. An intrusive force of 150g was applied after 10 days on the upper first molars using 6mm nickel-titanium closed coil spring. Pretreatment and posttreatment Lateral cephalograms and 3D Computed Tomography (CT) were measured and compared after a period of 9 months. Results: clinically showed the skeletal anterior open bite were all improvement, statistically analysis: cephalometrically, skeletal in three dimensions Antero-posterior a statistically significant increase in mean SN/Pog at P0.002, in group I, but decrease in mean value of SNB at P0.009, and increase in mean of SN/Pog at P0.001, in group II. Vertical decrease in the mean; SN/MP at P≤ 0.005, Ar-Go-Me P≤0.007, ANS-Xi-Pm P≤ 0.006, ANS-Me(mm) at p≤ 0.003 and N-Me(mm) at P≤ o.o11, while an increase in mean S-Go N-Me% at P≤ 0.016 in group I. Decrease in mean SN/MP at P≤ 0.008, PP/MP at P≤ 0.021, Ar Go Me at P≤ 0.004, ANS XI Pm at p≤ 0.003, N-ANS (mm) at P≤ 0.005, SN/PP at P≤0.002, ANS-Me at P< 0.001 and N-Me(mm) at P<0.001, while increase in mean value N-ANS/ANS-Me % at P<0.001, S-Go at P≤0.024 and S-Go/N-Me at P< 0.001 group II. dentoalveolar height decrease U6-PP at P≤ 0.001 while significant increase in mean overbite in both groups. Three dimensional computed tomographic (CT), decrease in mean intrusion (left side at P≤0.001 and right side at P≤0.001) in both groups, Conclusion: Miniscrew anchorage facilitated the correction of open bite by induced significant maxillary molar intrusion which caused counterclockwise rotation of both maxillary and mandibulary bases and also decrease in lower and total anterior facial heights.