Relapse of infective endocarditis usually occurs within two months of the discontinuation of antimicrobial therapy. The relapse rate for patients with native-valve endocarditis caused by penicillin-susceptible viridans streptococcus who have been treated with one of the recommended courses of therapy is generally less than 2 per cent. The relapse rate for patients with enterococcal native-valve endocarditis after standard therapy is 8 to 20 per cent. Among patients with infective endocarditis caused by Staph.aureus, Enterobacteriaceae, or fungi, treatment failure often occurs during the primary course of therapy. Positive culture at the time of valve-replacement surgery, particularly in patients with staphylococcal endocarditis, is a risk factor for subsequent relapse. The relapse rate in prosthetic-valve endocarditis is approximately 10 to 15 per cent, and relapse of infection may be an indication for combined medical and surgical therapy. Recurrence rate of NVE and PVE is around 4.5 - 7 per cent. In IVDA recurrent IE is around 43 per cent.