Medical benefits of cannabis have become widely accepted. In Obstetrics and Gynecology, it was reported to be useful to alleviate nausea and vomiting from morning sickness in pregnant women and in gynecologic cancer patients who received chemotherapy. It has also been used as a pain killer during labor and menstruation. Some also claimed that the cannabis may also prolong life of cancer patients or even cure cancer. Owing to the illegalization of the cannabis in many countries for a long time, there has been no evidence-based data from clinical study to support the use of cannabis for those aforementioned conditions except for chemotherapy induced nausea/vomiting. Systematics reviews confirmed that cannabis was significantly more effective than placebo and at least as effective as various conventional antiemetics. However, due to the availability of many potent new standard antiemetics (5-HT3 receptor antagonists, and neurokinin-1-receptor-antagonists) without psychotropic effects, cannabis is not recommended as a first-line antiemetic agent. The exception is when the new standard antiemetics cannot adequately control nausea and vomiting from chemotherapy. The cannabis is contraindicated in pregnant women or lactating mother because of the possibility of adverse fetal and neonatal outcomes. Once cannabis is legalized for medical use in more countries, its efficacy in those aforementioned conditions can be tested and confirmed in randomized controlled trials.