We aimed to investigate whether creatine supplementation affects the measured glomerular filtration rate in postmenopausal women (age, 58 ± 3 years). Subjects were randomly assigned to receive either creatine (20 g·day(-1) for 1 week and 5 g·day(-1) thereafter) or a placebo. Kidney function was assessed at baseline and after 12 weeks. [(51)Cr]EDTA clearance remained unchanged (CR-PRE: 86.16 ± 14.36 mL·min(-1) per 1.73 m(2), POST: 87.25 ± 17.60 mL·min(-1) per 1.73 m(2); PL-PRE: 85.15 ± 8.54 mL·min(-1) per 1.73 m(2), POST: 87.18 ± 9.64 mL·min(-1) per 1.73 m(2); p = 0.81). Thus, we concluded that creatine supplementation does not affect glomerular filtration rate in postmenopausal women.