Background Supracondylar humerus fracture in children is a very common elbow injury. The commonly accepted treatment of type II and III, extension-type supracondylar fractures of humerus in children is closed reduction with transolecranon pinning & lateral pinning. transolecranon pinning & lateral pinning has advantage of avoiding the possibility of iatrogenic ulnar nerve injury. Therefore, this prospective study was conducted to compare the stability of transolecranon pinning & lateral pinning and lateral pinning in treatment of type II and type III supracondylar humerus. Methods A prospective case series, was conducted at emergency department of Helwan university hospital and Elhelal Hospital from February 2020 to September 2021. It includes 30 patients below 10 years with Gartland types II and III supracondylar humeral fractures, the patients were divided into two equal groups; A and B. Patient treated by lateral pin and transolecranon pin were kept in Group A and those treated with 3 lateral pins in Group B, all of them were included for the study and analysis of results regarding Functional outcome was graded according to Flynn`s criteria and Baumann’s angle. Results Thirty children were treated for displaced supracondylar fracture of humerus during the study period male six patients in group A and 10 patients females in group B with a mean age 5.43±1.699 in group A; a mean age 5.16±1.789 in group B, The mean follow up duration was 2.9000 ± 2.07364 ( 6 months). In lateral and transolecranon pinning group (9) patients with excellent results and (5) patient was good and (1) patient was fair, in lateral pinning technique (14) patients with excellent results and (1) patient was fair. Conclusion There was statistically no significant difference between transolecranon pinning and lateral pinning and lateral pinning technique regarding carrying angle, time of surgery and flexion loss.