Widespread use of smartphones and wireless internet have made YouTube an easily accessible educational modality. Many residents use YouTube to acquire knowledge regarding microsurgical techniques; however, its quality and effect has not been verified. We included 22 residents working in the Department of Plastic and Reconstructive Surgery at our institute. Using block randomization, seven were allocated to a textbook group (TG), eight to a free-searching group (FSG), and seven to a designated-video group (DVG). After reviewing textbooks, YouTube videos, or designated videos, respectively, each group performed microsurgical anastomosis using artificial vessels. The total procedure time, Objective Structured Assessment of Technical Skills (OSATS), operative errors, and degree of leakage were assessed by blinded evaluators. Self-confidence rates were also compared. The YouTube groups (FSG and DVG) performed better than the TG. Although procedure time was significantly longer in the DVG (p = .006), the performance of DVG was better than that of TG in all assessments (OSATS: p = .012; operative errors: p = .002; leakage: p = .010). FSG showed more operative errors (p = .004) and leakage (p = .007) compared to DVG, but had higher OSATS (p = .008) and fewer operative errors (p = .002) than TG. The post-intervention confidence rates were significantly higher in FSG and DVG compared to TG (p = .002 and p = .001, respectively). Although there are concerns regarding the reliability of YouTube videos, microsurgery videos on YouTube had positive effects on microsurgery practice. Therefore, YouTube may help to improve the microsurgical skills of residents. If a quality control system is introduced for YouTube videos, their educational effects may be enhanced.