Epidemiologic studies have shown that serum level of adiponectin, a circulating protein secreted by adipocytes, predicts the risk of type 2 diabetes and cardiovascular events. Two single-nucleotide polymorphisms (SNPs) at the adiponectin locus (T45G or G276T) of the adiponectin gene (APM1) have been associated with insulin resistance, low serum adiponectin levels, and diabetes. In the present study, the association of these polymorphisms with serum adiponectin level and insulin resistance-associated risk factors was investigated. To this aim, SNP+45 and SNP+276 of APM1 were genotyped in 252 young Finnish men. Serum adiponectin level (p < 0.001) and diastolic blood pressure (p = 0.031) were significantly higher in subjects with the T276T genotype of APM1 compared to those with the G276T or G276G genotypes. Mean diastolic blood pressure among the T276T subjects was 80 mmHg and that in subjects with the G276G and G276T genotypes below 75 mmHg. An interaction between triglycerides, diastolic blood pressure, quantitative insulin sensitivity check index, and SNP276 with regard to serum adiponectin level was found. After adjustment for other covariates, the interaction between triglycerides and SNP276 remained statistically significant (p = 0.009). Among subjects with the T276T genotype, an increase in triglyceride level was associated with a decrease in adiponectin concentration. This result was not observed in other genotype groups. SNP+45 was not significantly related to serum adiponectin concentration, but high-density lipoprotein (HDL) cholesterol tended to be higher in subjects with the T45T genotype (p = 0.051) compared to subjects with the X45G genotype. In conclusion, the T276T genotype of the adiponectin gene was associated with elevated serum adiponectin level and diastolic blood pressure among young Finnish men.