Objective: The functional 577R allele of the α-actinin-3 (ACTN3) gene has been reported to be associated with elite power athlete status, while the nonfunctional 577XX genotype (predicts an α-actinin-3 deficient phenotype) has been hypothesised as providing some sort of advantage for endurance athletes. In the present study, the distribution of ACTN3 genotypes and alleles in Russian endurance-oriented athletes were examined and association between ACTN3 genotypes and the competition results of rowers were sought. Methods: 456 Russian endurance-oriented athletes of regional or national competitive standard were involved in the study. ACTN3 genotype and allele frequencies were compared with 1211 controls. The data from the Russian Cup Rowing Tournament were used to search for possible association between the ACTN3 genotype and the longdistance (∼6 km) rowing results of 54 athletes. DNA was extracted from mouthwash samples. Genotyping for the R577X variant was performed by PCR and restriction enzyme digestion. Results: The frequencies of the ACTN3 577XX genotype (5.7% vs 14.5%; p<0.0001) and 577X allele (33.2% vs 39.0%; p = 0.0025) were significantly lower in endurance-oriented athletes compared with the controls, and none of the highly elite athletes had the 577XX genotype. Furthermore, male rowers with ACTN3 577RR genotype showed better results (1339 (11) s) in long-distance rowing than carriers of 577RX (1386 (12) s) or 577XX (1402 (10) s) genotypes (p = 0.016). Conclusion: Our data show that the ACTN3 577X allele is under-represented in Russian endurance athletes and is associated with the rowers' competition results.