The following thesis applies the BestBETS method in order to discuss a clinically structured question regarding the use of beta-blockers in Tetralogy of Fallot patients. This paper scans the available medical literature for evidence that such use of drugs is beneficial in the prevention and treatment of cyanotic spells in the pre-operative patient with Tetralogy of Fallot. The results demonstrate the shortage in adequate evidence in the field of Pediatric Cardiology.