BACKGROUND: Nocturia is the most prevalent lower urinary tract symptom in women, affecting approximately 54.5% of female patients and significantly impacting the quality of life. While the androgen levels may be related to urinary function, its association with nocturia in women remains unclear. This study aims to explore the relationship between androgen levels and nocturia in women. METHODS: This study utilized data from the 2013-2016 National Health and Nutrition Examination Survey (NHANES), including 4531 women aged 20 and above. The level of androgen is reflected by the total testosterone (TT) and free androgen index (FAI). Weighted logistic regression models were employed to analyze the association between FAI, TT, and nocturia. RESULTS: After comprehensive adjustment for confounding factors, higher FAI levels were significantly associated with a reduced risk of nocturia (OR = 0.84, 95% CI: 0.74-0.95). Women in the highest FAI tertile had a significantly lower incidence of nocturia compared to those in the lowest tertile (OR = 0.75, 95% CI: 0.60-0.93). Trend analysis indicated a significant decrease in nocturia occurrence with increasing FAI levels (P for trend = 0.0177). No significant association was found between TT levels and nocturia. CONCLUSIONS: Higher FAI levels are significantly inversely associated with nocturia in women, suggesting that bioavailable testosterone may have a protective effect against nocturia. This finding underscores the importance of considering FAI levels in research and clinical practice, and future studies should explore the potential benefits of modulating FAI levels in women with nocturia.