Precision medicine requires a different type of clinical trial that focuses on individual responses to therapy, rather than average responses. Current clinical trials often fail to help a significant portion of patients, and there is a growing interest in "precision" medicine to address this issue. The US government has launched a $215 million Precision Medicine Initiative, including the establishment of a national database of genetic and other data from one million people. N-of-1 trials, which focus on a single individual, are crucial for understanding individual responses to treatments. These trials involve collecting detailed data over an extended period, using appropriate control interventions, and comparing the effects of different treatments. Formalizing and scaling up N-of-1 trials requires solving practical problems such as developing new health-monitoring devices and identifying appropriate biomarkers. While N-of-1 trials can provide more personalized treatment options, they face significant barriers, including regulatory concerns, high costs, and the need for better biomarkers and study designs. However, there is growing support from regulatory agencies and pharmaceutical companies, and patient engagement is key to making precision medicine mainstream. N-of-1 trials can help reduce the cost of inappropriate interventions and improve the effectiveness of drug development and treatment.Precision medicine requires a different type of clinical trial that focuses on individual responses to therapy, rather than average responses. Current clinical trials often fail to help a significant portion of patients, and there is a growing interest in "precision" medicine to address this issue. The US government has launched a $215 million Precision Medicine Initiative, including the establishment of a national database of genetic and other data from one million people. N-of-1 trials, which focus on a single individual, are crucial for understanding individual responses to treatments. These trials involve collecting detailed data over an extended period, using appropriate control interventions, and comparing the effects of different treatments. Formalizing and scaling up N-of-1 trials requires solving practical problems such as developing new health-monitoring devices and identifying appropriate biomarkers. While N-of-1 trials can provide more personalized treatment options, they face significant barriers, including regulatory concerns, high costs, and the need for better biomarkers and study designs. However, there is growing support from regulatory agencies and pharmaceutical companies, and patient engagement is key to making precision medicine mainstream. N-of-1 trials can help reduce the cost of inappropriate interventions and improve the effectiveness of drug development and treatment.