One in five Canadians will experience some form of mental illness in their lifetime. Treatments are available but each person responds differently to them, in part because of their genes. A clinically proven genetic test, called GeneSight, analyzes an individual’s genes and recommends the optimal drugs for that person along with dose adjustments among the 33 most commonly prescribed antidepressant and antipsychotic drugs. Clinical testing in the United States has shown that GeneSight doubles the odds of a patient responding to antidepressant medication. More than 100,000 patients have received GeneSight tests in the United States. Now, Assurex Health, the company that developed GeneSight, is partnering with scientists at Toronto’s Centre for Addiction and Mental Health (CAMH) to develop the Enhanced GeneSight (E-GeneSight) genomic test. E-GeneSight will incorporate new genomic markers that scientists at CAMH have identified and characterized for their association with patient responses to psychiatric medications. Assurex Canada and CAMH will together validate these markers for their ability to predict efficacy and side effects of psychiatric medications; the most predictive markers will be integrated into E-GeneSight. E-GeneSight, when launched in 2017, is anticipated to reduce the need for “trial-and-error” approaches to prescribing and increase the likelihood that people will respond optimally to the medications prescribed for them, while reducing side effects. This will increase the proportion of patients who stay on their medications and improve their quality of life. It will also save the Canadian healthcare system $4,000 per year per treatment-resistant patient and will generate royalty revenues for CAMH as E-GeneSight is marketed internationally.