INTRODUCTION: Lifelong premature ejaculation (LPE) is characterized by persistent intravaginal ejaculation latency times (IELTs) of less than 1 min, and has been postulated as a neurobiological dysfunction related to diminished serotonergic neurotransmission with 5-HT₁A receptor hyperfunction and 5-HT₂C hypofunction. AIM: To investigate the relationship between 5-HT₁A receptor gene (HTR₁A)-C(1019)G promoter polymorphism and IELT in men with LPE. This polymorphism is known to increase 5-HT1A receptor expression. METHODS: A prospective study was conducted in 54 Dutch Caucasian men with LPE. Baseline IELT during coitus was assessed by stopwatch over a 1-month period. All men were genotyped for HTR₁A gene polymorphism. Allele frequencies and genotypes of C and G variants of HTR₁A polymorphism were determined. Association between CC, CG, and GG genotypes and the IELT in men with LPE were investigated. MAIN OUTCOME MEASURES: IELT measured by stopwatch, HTR₁A polymorphism. RESULTS: In this cohort of men with LPE, the geometric mean IELT was 23.8 s. Of the 54 men, the CC, CG and GG genotype frequency for the C(1019)G polymorphism of the 5-HT₁A gene was 33%, 43% and 24%, respectively. The geometric mean IELT for the CC, CG and GG genotypes were 14.5, 27.7 and 36.0 s, respectively (p=0.019). Compared to GG and CG genotypes, men with CC genotype had a 250% and 190% shorter ejaculation time, respectively. CONCLUSIONS: HTR₁A gene polymorphism is associated with the IELT in men with LPE. Men with CC genotype have shorter IELTs than men with GG and CG genotypes.