Aims: To investigate the success rate of oral fluorescein angiography (oral FA) in children with ultrawide scanning laser ophthalmoscopy (SLO) system and whether it can provide images of sufficient quality compared with intravenous FA (IVFA). Methods: In this comparative case series study, a series of 40 consecutive pediatric patients of the age of 3–18 with retinal vascular diseases, in whom FA was needed for the diagnosis or treatment, were enrolled in this study. IVFA and oral FA were performed within one week and images were obtained with the SLO system. The image quality was scored blindly and compared based on: (I) visualization of the branch retinal vessel, (II) the foveal avascular zone (FAZ), and (III) clinically important findings, such as the presence of microaneurysms, neovascularization, leakage, or significant nonperfusion. All these were scored using a three-point scale. Results: In preschoolers (three to six years), all 19 children complete oral FA (100%), while only 7 (36.84%) complete IVFA (p < 0.0001). With the SLO system, the branch retinal vessels were well visualized both in oral and IV FA (all images were two scores). The visualization of FAZ was similar between oral and IV FA (p = 0.8972). The clinically important findings were well visualized in both groups (p > 0.9999). The overall image quality was similar between the two groups (p = 0.2500). Conclusion: Oral FA is more acceptable to preschoolers than IVFA owing to the needle-free procedure. With the SLO system, oral FA provided high-quality angiograms similar to IVFA. Oral FA is an effective alternative to IVFA and may be considered the first option for FA in pediatric patients, especially in preschoolers.