During pregnancy, infective endocarditis (IE) is quite rare but has a high mortality rate in terms of the mother and the fetus. In this article, a 24-year-old patient with a history of mitral valve prolapse (MVP) who was hospitalized due to IE and treated successfully is presented. On echocardiography, severe mitral valve prolapse, severe mitral regurgitation, and vegetation on the posterior leaflet of mitral valve were observed. Streptococcus mitis was subsequently isolated from four sets of blood cultures. The patient was diagnosed with IE. After 6 weeks of antibiotic therapy, the patient was cured completely without surgical treatment. At 40-weeks of pregnancy, the patient gave birth via a normal vaginal delivery. There were no problems with the 3,800-gram baby born. In current guidelines, there is very limited advice on treatment options for patients who develop IE during pregnancy. Therefore, evaluation of patient-based treatment options would be appropriate. In addition, IE prophylaxis for MVP is not recommended in current guidelines. However, in MVP patients with mitral regurgitation, prior to procedures associated with a high risk of infective endocarditis, IE prophylaxis may be rational.