Being a great threaten for human health, obesity has become a pandemic chronic disease. There have been several therapeutic treatments for this social health issue, including diet and exercise therapy, medication and surgery, among which the diet is still the most common way. However, none of these therapeutic measures available is ideal, making it necessary to find an effective medical treatment. The endocannabinoid system, which is well known for its contributions in certain mental processes such as relaxation, amelioration of pain and anxiety, and sedation initiation, has been recently reported to play an essential role in regulating appetite and metabolism to maintain energy balance, leading to the belief that endocannabinoid system is closely related to obesity. This new discovery deepens our understanding of obesity, and provides us with a new direction for clinical obesity treatment. Rimonabant is an antagonist for CB1, and has entered the market in some countries. However, although effective as an anti-obesity drug, rimonabant also causes obviously adverse side-effects, thus is being doubted and denied for medical usage.Keywords: obesity; weight loss; endocannabinoids; cannabinoid receptor; cannabinoid CB 1 receptor antagonist; anti-obesity agents; rimonabant As a chronic disease with multi-pathogenesis and a variety of complications, obesity is characterized by excess accumulation of body fat, as measured by "body-mass index" (BMI), for which the body weight of an individual is divided by the square of his height. According to the definition made by World Health Organization (WHO), one whose BMI is within the range of 25-29.9 kg/m 2 is defined as overweight, while within the range of 30.0-39.9 kg/m 2 is defined as obesity, and one whose BMI is 40 kg/m 2 or above is considered as morbid obesity. In the past, overweight and obesity were considered as health concerns only in developed countries. However, with the development of living qualities, more and more people, especially the young, tend to get obesity in both developed and developing countries, and their health is endangered [1,2] . In 1999, obesity was officially documented as a preventable disease by WHO, and it has become the second lethal risk for human life following smoking. Obesity, together with AIDS, drug addiction and alcohol abuse, is considered the four major worldwide medical issues. [3,4] .The current available treatments for obesity include diet and exercise therapy, medication and surgery, and the first one remains the most common. However, it's always easy to lose weight at a moderate level but very hard to keep, as proved by the report that weight loss typically peaks 6 months after treatment; however, by the end of the year, one third of the lost weight has been regained, and usually all the lost weight is regained within 5 years [4,5] . That is, lifestyle intervention seldom works well. Meanwhile, no obesity treatment has been approved by FDA, although a handful of approved medications for illness other than obesity, s...