To become a medical marijuana patient in Illinois, you must follow these steps: Obtain a written certification from a physician that you have been diagnosed with a qualifying condition. These conditions include chronic pain, cancer, HIV/AIDS, and several others. Register with the Illinois Department of Public Health (IDPH) by completing the online application. You will need to provide your personal information, proof of Illinois residency, and a copy of your physician's certification. Once your application has been approved, you will receive a medical marijuana card in the mail. Visit a dispensary with your medical marijuana card to purchase cannabis products. Note that you will need to renew your medical marijuana card every three years. It's worth noting that there are some alternative options available, like telemedicine and online certification, you should check the website of the Illinois Department of Public Health for more information and for any updates, as the laws are subject to change.