Rimonabant is an anorectic anti obesity drug. It is a CB1 cannabinoid receptor antagonist. Its main avenue of effect is reduction in appetite. Obesity is now the most common nutritional disorder in western countries. Defined as a body mass index of greater than 30, it arises from the accumulation of excess fat in the body from overconsumption of fatty foods. Prevalence of obesity in the US and Europe has reached epidemic levels. Data from the World Health Organisation's MONICA project show that in some parts of Europe over 70% of men aged 55-64 years are clinically obese or overweight (BMI >25) and almost 70% of women in this age group. One in five of all Americans is obese and one in three overweight. Furthermore, increasing rates of childhood obesity are likely to exacerbate the trend towards increasing obesity in adulthood.