This paper reviews key studies that have addressed genetic and neurobiological aspects in attention deficit hyperactive disorder. Genetic studies can be divided into three distinct types: twin, adoption, and family studies. Evidence for a particular mode of inheritance and the possible specific genetic abnormalities are also explored. There is strong evidence of genetic involvement in this condition, although a clear-cut mode of inheritance and specific genetic abnormalities are yet to be determined. Neurobiological aspects such as the neuroanatomical and neurochemical evidence of various neurotransmitter system involvement is explored. Frontal lobe and dopamine and norepinephrine neurotransmitter systems appear to be involved in attention deficit hyperactive disorder.