Mental workload is an abstract concept that perceives cognition as the brain having a small and finite capacity to process information, with high levels of workload associated with poor performance and error. While an individual may be able to complete two different tasks individually, a combination of tasks may lead to cognitive overload and poor performance. In many high-risk industries, it is common to measure mental workload and then to redesign tasks until cognitive overload is avoided. This study aimed to measure the effect of multitasking on the mental workload and performance of medical students completing single and combined clinical tasks.