ABSTRACT BACKGROUND: Teleradiology consists of electronic transmission of radiological images from one location to another, including between countries, for interpretation and/or consultation. It is one of the most successful applications of telemedicine. Combining this methodology with ultrasound (called telesonography) can accelerate the process of making diagnoses. Despite this rationale, the quality of the evidence about the effectiveness and accuracy of teleradiology remains unknown. OBJECTIVE: To review the literature on the evidence that exists regarding use of telemedicine for ultrasound in situations of synchronous transmission. DESIGN AND SETTING: Narrative review conducted within the evidence-based health program at a federal university in São Paulo (SP), Brazil. METHODS: A search of the literature was carried out in April 2020, in the online databases MEDLINE, EMBASE, Cochrane Library, Tripdatabase, CINAHL and LILACS, for original publications in all languages. The reference lists of the studies included and the main reviews on the subject were also evaluated. RESULTS: We included ten studies that assessed procedures performed by different healthcare professionals, always with a doctor experienced in ultrasound as a distant mentor. Among these, only one study assessed disease diagnoses in relation to real patients. CONCLUSIONS: Despite the promising position of telesonography within telemedicine, no studies with reasonable methodological quality have yet been conducted to demonstrate its effectiveness.