The aim of this study was to quantify the long-term reversibility of kidney function decrease occurring during hospitalization and treatment for infective endocarditis (IE). A prospective observational cohort study was performed at a tertiary university hospital in Copenhagen from October 2002 through May 2008; 223 consecutive IE patients were included. Forty patients died in hospital and 38 within 1 y of discharge. Of the 145 patients called in for the 1-y follow-up, 111 accepted. Kidney function was assessed by estimated endogenous creatinine clearance (EECC). Statistical correlation between EECC at admission, discharge and follow-up, as well as correlations between gentamicin and EECC changes, were analyzed. In the 111 follow-up patients, the bacteriological aetiologies were: Streptococcus species (47.7%), Enterococcus (16.2%) and Staphylococcus aureus (11.7%). The mean EECC decrease from admission to discharge was 8.4% (95% confidence interval 1.6-15.2; p <0.001). However this kidney function impairment was reversed at the 1-y follow-up. When divided into subgroups, a full kidney function restitution was seen in only 35.1% of patients with an EECC decrease of >22%. In conclusion, kidney function impairment occurring during hospitalization for IE is potentially reversible within the first y post-discharge.