The Biological approach to abnormality regards a mental disorder as an "˜illness' rather then a "˜disease.' This is because mental disorders are thought to be related to the physical structure and functioning of the brain. According to this model of abnormality, mental disorders are thought to have an organic basis, such as a brain tumour.

The biological understanding of mental disorders include the role played by biochemicals. Functional disorders are now also thought to be physical in origin, symptoms occurring as a consequence of biochemical changes in the brain, which result in a dysfunction of neurotransmitters.

Genetic research has highlighted that some people may be genetically at risk of developing a mental disorder as it passes through generations through DNA. Individuals may inherit predisposition's to certain illnesses. These predisposition's are carried on through genes which pass from one generation to the next.

The Biological model suggests that because mental problems are viewed as a physical illness, then physical treatments seem the most appropriate to use. Chemotherapy is the use of psychotherapeutic drugs but chemicals in this drug affects the functioning of certain neurotransmitters in the brain. There is also electro-convulsive therapy and procedures such as a lobotomy where certain areas of the brain are removed. However, such therapies can leave the patient in a "˜zombie-like' state.

Many psychologists criticise psychiatry for focusing its attention on the symptoms of an illness and assuming by relieving those symptoms with drugs relieves the problem. The role of psychological and social factors are ignored. This is especially important because many of the symptoms of mental disorders are given in psychological and social terms and therefore the application of medical principles in inappropriate. It seems that the drugs are not actually curing the actual cause of the problem but just relieving the symptoms. Another criticism of this model is that people become patients and their well being is in the care of professionals who may be mistaken in diagnosing their illness.