We planned to compare individuals with alcohol dependence (AD) and healthy controls on the frequency of NOS1 exon 1f-VNTR gene polymorphism and to investigate the effects of this polymorphism on the clinical symptoms of alcohol dependence, impulsiveness and comorbid attention deficit hyperactivity disorder (ADHD) symptoms.A total of 282 participants consisting of 153 patients and 129 age and gender matched healthy individuals were inluded in the study. All participants were evaluated with Structured Clinical Interview for DSM-IV Axis 1 disorders (SCID-I) and Michigan Alcohol Screening Test (MAST), Barratt Impulsiveness Scale (BIS-11), UPPS Impulsive Behavior Scale, Adult Attention Deficit and Hyperactivity Diagnosis Scale (ADHDS), Family History Research Diagnostic Criteria (FHDRC). The QF-PCR fragment protocols were used for genetic analyses. Allele fragments of ≤176 bp and >176 bp sizes were separated and 3 different genotypes were determined as the SS, SL and LL. Associations of these genotypes with symptoms of AD severity, impulsiveness and comorbid ADHD were investigated.The AD and control groups did not differ significantly on the basis of NOS1 exon 1f-VNTR gene polymorphism. Also, significant correlations between this polymorphism and symptoms of AD severity, impulsiveness and ADHD were not determined.Results of our study do not indicatea significant association between the NOS1 exon 1f-VNTR genotypes and AD, subgroups of AD, impulsiveness or comorbid ADHD semptoms.