VA Medicinal Cannabis Research Act of 2023 This bill requires the Department of Veterans Affairs (VA) to study the effects of cannabis on veterans who are enrolled in the VA health care system and have been diagnosed with post-traumatic stress disorder (PTSD) or chronic pain (i.e., eligible veterans). First, the bill requires the VA to conduct an observational, 18-month study on the effects of cannabis on the health outcomes of eligible veterans. The VA must report on the study and address whether it is able to meet criteria necessary to conduct clinical trials. Then, if the VA determines that it is able to proceed, it must carry out a series of clinical trials on the effects of cannabis appropriate for investigational use, as determined by the Food and Drug Administration, on the outcomes of eligible veterans. The VA must carry out a long-term observational study of the clinical trial participants. The VA may terminate the trials if it is unable to meet clinical guideline requirements or the trials would create excessive risk to participants. The VA must ensure that the study and trials are representative of the demographics of veterans in the United States, as determined by the most recent data from the American Community Survey of the Bureau of the Census. The study and trials must include mechanisms to ensure data preservation and registration as necessary (in an anonymous form).