Suicide is a complex human behaviour challenging not only for medicine and psychiatry but the whole society as well. Although our knowledge is expanding concerning the underlying factors of suicidal behaviour, we still do not have sufficient knowledge concerning its biochemical, neuroanatomical and genetic background. Genetic determinants of suicidal behaviour may lead to the emergence of such personality traits and temperaments which may be long-time predictors of suicide. One of the most likely genetic candidates in the background of suicide is the 5-HTTLPR polymorphism of the serotonin transporter gene. Although there are contradicting results, several studies and metaanalyses support that the s allele plays a role in the background of violent suicide. However, in order to be able to delineate the genetic background of suicide, different types of suicidal behaviour should be distinguished, since studies indicate that these may have different genetic factors. Also, personality traits and temperaments should be identified which may play a modulating role between genetic factors and suicidal behaviour. So far, neuroticism, affective temperaments, and impulsive aggression have been found to be associated with both the s allele and suicidal behaviour. In order to gain deeper insight to the genetic determinants of suicidal behaviour we must determine intermedier endophenotypes modulating between genetic factors and manifested suicidal behaviour.