Background: The C1019T polymorphism of the connexin-37 (GJA4) gene is a single-nucleotide polymorphisms involved in atherosclerotic plaque rupture and atherosclerosis predisposition. We examined the association between the C1019T polymorphism of the GJA4 gene and the occurrence of myocardial infarction (MI) in patients with premature coronary artery disease (CAD). Methods: Our study recruited 1000 patients with the final diagnosis of premature CAD and classified them into 2 groups: with a history of MI (n = 461) and without it (n = 539). The polymorphism variants were determined via the PCR-RFLP, and then genotyping was conducted through the high-resolution melting method. From a total of 1000 patients, 554 patients, who had been previously followed-up with a median follow-up time of 45.74 months vis-à-vis long-term major adverse cardiac events, were enrolled in this retrospective cohort phase. Results: The frequencies of the wild, heterozygous, and mutant genotypes of the C1019T polymorphism were 54.0%, 40.6%, and 5.4% in the MI group and 49.2%, 43.2%, and 7.6% in the non-MI group (p value = 0.187). After adjustment for the baseline covariates, no difference was found between the MI and non-MI groups apropos the frequency of the heterozygous genotype (p value = 0.625) and the mutant genotype (p value = 0.452). Regarding the level of human connexin-37, the serum level of this marker was not different between the MI and non-MI groups. Conclusion: The C1019T polymorphism of the GJA4 gene may not be useful for predicting the occurrence of MI in patients with premature CAD. The presence of this polymorphism in such patients may also have a low value for predicting long-term CAD complications.