ABSTRACT Objective This study was performed to monitor and evaluate the safety, patient comfort and efficacy of sedated transesophageal echocardiography (TEE), which was compared with conventional TEE only with topical oropharyngeal anaesthesia. Methods Between August 2018 to August 2019, 116 patients (67 males with an average age of 47±15 years) referred to conventional TEE and 80 patients (37 males with an average age of 44±16 years) referred to sedated TEE were included. The exclusion and inclusion criteria were complied with 2013 TEE guideline of ASE. During the whole examination, the following indicators were monitored and recorded, 1) heart rate, blood pressures and oxygen saturation changes; 2) success rate of one-time intubation, examination time and complications ; 3) image satisfaction; and 4) the level of patient discomfort. The results of the two groups were compared and statistically analyzed．Results In sedated TEE group, ASA score was higher than that of conventional TEE group (P<0.05), LVEF was lower than that of conventional TEE group (P<0.05). There was significant difference in clinical indication distribution between the two groups (P<0.05). In the conventional TEE group, the heart rate and blood pressures increased significantly during examination(P<0.05), which were reduced after exmamination but still slightly higher than those before examination. In the sedated TEE patients, the heart rate, systolic and diastolic blood pressures during examination were reduced compared with baseline pressures (P＜0.05). However, there was significant increase of the heart rate and blood pressures after examination (P＜0.05). The success rate of one-time intubation in sedated TEE group was higher than that in conventional TEE (Sedated VS Conventional: 87.5% VS 75.9%, P＜0.05), the examination time was significantly longer than that of the conventional TEE group (Sedated VS Conventional: 13.2±4.4min VS 5.3±2.0min, P＜0.05). 98.8% cases in sedated TEE group had satisfactory images, while only 65.5% patients in conventional TEE . The VAS score in sedated TEE group was significantly reduce compared with conventional TEE group (0.4±0.8 VS 3.3±1.7; P＜0.01). And the willing to receive TEE examination again in sedated group was significantly higher than that of the conventional TEE group (Sedated VS Conventional: 92.5% VS 51.7%; P＜0.01). Conclusions Sedated TEE is a safe and effificient examination. Compared with conventional TEE, it is suitable for patients with more serious conditions, and can obviously improve the patient comfort and image qualities during TEE, which contributed to the precise clinical diagnosis and treatment evaluation.