The association between high and low levels of emotional reactivity (ER) as a temperamental trait and the dopamine D4 receptor (DRD4) exon III polymorphism in healthy men aged 18 to 27 (M= 21.03, SD = 2.23) was examined. ER, measured by the Formal Characteristics of Behavior–Temperament Inventory (FCB-TI), is defined as a tendency to react intensively to emotion-generating stimuli and is expressed in high emotional sensitivity and in low emotional endurance. Data analysis demonstrated a statistically significant difference in the distribution of genotypic frequencies between the low and high ER groups: χ2 = 4.88; df = 1; p = .027, odds ratio (OR) =2.85, 95% confidence interval (CI) = 1.11–7.32. An insignificant difference in allele frequencies between the two groups was noted: χ2 = 7.47; df = 3; p = .058; OR = 2.9, 95% CI = 1.29–6.53. These findings suggest a role of the DRD4 exon III polymorphism in the modulation of ER as a temperamental trait. Due to the preliminary nature of our findings, replication is necessary.