Clinical guidelines recommend a single-pool Kt/V of 1.2–1.4 per session, but gender-specific target values remain undefined. This study evaluated the association between Kt/V and mortality in Korean maintenance hemodialysis (HD) patients. We used HD Quality Assessment and National Health Insurance Service claims data from October through December 2015. A total of 29,349 patients who participated in the 2015 HD Quality Assessment were included in the study. Patients were categorized by Kt/V: <1.2, 1.2-1.4, 1.4-1.7, and ≥1.7. The association between Kt/V and all-cause mortality was assessed using a Cox proportional hazards model. In the Cox analysis, the Kt/V range of 1.2–1.4 was defined as the reference group. Among the total patients, 17,171 (58.5%) were male, and 9,178 (41.5%) were female. The mean follow-up period was 53.8±23.0 months. The mean Kt/V was 1.44±0.22 in men and 1.71±0.27 in women. Higher Kt/V was associated with reduced mortality, with a greater effect in women (hazard ratio [HR] 0.66, 95% confidence interval [CI] 0.58-0.75 per 0.1 Kt/V) than in men (HR 0.80, 95% CI 0.70-0.90 per 0.1 Kt/V). In male, a Kt/V <1.2 was associated with an increased mortality (HR 1.25, 95% CI 1.14-1.37) compared to the reference group, whereas no significant difference in mortality was observed for Kt/V ≥1.4. In female, a Kt/V ≥1.4 was associated with a lower mortality (1.4-1.7, HR 0.86, 95% CI 0.78-0.96; ≥1.7, HR 0.73, 95% CI 0.65-0.82) compared to the reference group, while no significant difference in mortality was observed for Kt/V <1.2. The study found that a Kt/V ≥1.2 was associated with improved survival in men, and a Kt/V ≥1.4 was associated with better survival in women. This study provides real-world evidence that the optimal Kt/V varies based on gender. Further research is needed to elucidate the rationale for gender-specific Kt/V targets.