A 22-year-old woman was admitted to our hospital with high fever and lumbar pain. Echocardiography revealed mitral regurgitation due to prolapse of the anterior mitral leaflet. On admission, her white blood cell count was high and results for C-reactive protein were positive. The blood culture was positive for hemolytic streptococcus. After the white blood cell count and C-reactive protein level were normalized, and the blood culture had become negative following treatment by multiple antibiotics, she underwent valvular surgery. Because the infectious lesion was limited to the mitral leaflet and chordae, mitral valvuloplasty was performed with a satisfactory postoperative result. The operative technique consisted of resection of the infected valvular tissue, implantation of artificial chordae with e-PTFE, and suture annuloplasty. To conclude, mitral valvuloplasty should be the operative method of choice in patients with infective endocarditis, especially in young women with the potential of future pregnancy and labor.