Background Three-dimensional (3D) printed cardiac models are increasingly being utilised for medical education, simulation and training, communication, surgical planning and research. Due to the complexities of congenital cardiac anatomy, 3D printing is well suited as an adjunct to traditional teaching methods. We hypothesised that using 3D printed cardiac models as an adjunct to didactic teaching methods would improve knowledge and confidence levels of participants, regardless of their cardiology experience. Methods A prospective randomised study was performed recruiting paediatric nurses and doctors. All participants undertook traditional congenital cardiac teaching describing normal cardiac anatomy and seven congenital lesions of increasing complexity (atrial septal defect (ASD), ventricular septal defect (VSD), vascular ring, partial anomalous pulmonary venous return (PAPVR), Tetralogy of Fallot (TOF), transposition of the great arteries (TGA) and double outlet right ventricle (DORV)). The intervention group received an additional recorded demonstration, while handling 3D printed models of a normal heart and the same lesions. Pre and post-intervention assessments were completed using a subjective Likert scale questionnaire and objective multiple choice examination. Results Seventy-three health practitioners, (30 cardiac nurses and 43 paediatric trainees) were included. A significant increase in subjective confidence (mean score of 2.7 (SD 0.88) to 3.3 (0.71), increase of 0.58 vs 2.5 (1.0) to 2.6 (0.87), increase of 0.06, pDiscussion 3D printed cardiac models significantly improve subjective and objective confidence towards and knowledge of a range of congenital cardiac lesions for both nurses and paediatric trainees. 3D cardiac models are a useful adjunct to traditional teaching methods as they overcome limitations with 2D representations of 3D structures, provide additional educational opportunities in a scarce learning environment and are consistent with adult learning principals. As barriers to production and access are overcome, 3D printed cardiac models should be incorporated more widely in medical education programs.