Recent studies have reported the prognostic implications of the discordance between creatinine-based and cystatin C-based estimated glomerular filtration rates (eGFRcr and eGFRcys, respectively); however, the associations of protein intake with the eGFR discordance have not been investigated. The present study investigated whether protein intake was associated with the discordance between eGFRcr and eGFRcys.