Abstract The serotonergic neurotransmission was suggested to play an important role in the aetiology of alcoholism. This study explores the association between tryptophan hydroxylase (TPH)-alleles and Loudness Dependence of Auditory Evoked N1/P2 Potentials (LDAEP). The TPH is the rate-limiting biosynthetic enzyme in serotonergic pathway. The LDAEP is one of the best validated non-invasive indicators for serotonergic neurotransmission. A sample of 54 alcoholics was recruited. N1/P2 potentials were evoked by five different sound intensities. A dipole source analysis using BESA (brain electric signal topography) was performed and intensity dependence was computed. The TPH intron 7 polymorphism was determined by using PCR in DNA samples. There was a weak but significant association between low LDAEP and the L-TPH allele. No influence from an individual's history of alcohol dependence or a positive family history of alcohol dependence on LDAEP was found. The weak but significant relationship found between L-TPH-allele and high serotonergic neurotransmission may contribute to a more detailed neurobiological characterization of alcohol dependents using functional and genetic parameters.