Serotonergic neurotransmission has been implicated in suicidal behavior. Polymorphisms in the genes coding for tryptophan hydroxylase, serotonin receptor 2A and serotonin transporter were investigated in a sample of suicide attempters (n = 165) and healthy control subjects (n = 99). No significant differences were found for any of the investigated polymorphisms. Neither did any significant differences emerge in comparison with control subjects when the suicide attempters were grouped into different diagnostic categories: unipolar disorder (n = 45), adjustment disorder (n = 37), substance use disorder (n = 37) and personality disorder, cluster B (n = 36). The results suggest that alleles defined by the investigated polymorphisms do not represent a major determinant in suicide attempt. However, a highly significant (P = 0.001; odds ratio, 1.47; 99% confidence interval, 1.42-1.53) allelic association between tryptophan hydroxylase and suicide attempt is indicated after pooling our data with literature data. In light of previous data, a possible association between the tryptophan hydroxylase polymorphism and a phenotype that may become differently stratified within differently selected samples of suicide attempters is discussed.