This article about accountability of hospitals for medical malpractice in relation whit the medical service is a sociologist research about the legal principle, norm and various legal definition concerning contractual law, tort and judicial decision related to accountability by the hospital for medical malpractice. The result of research at Dr. Sardjito Hospital and a public hospital in the Sleman subdistrict of Yogyakarta shows that relation between hospital and doctor in the medical service execution is legal relationship based in giving medical service. In the execution of the medical services by doctor in the hospital, the doctor bears full responsibility for the rights and duties. The complete freedom in exercising his rights and responsibilities of the doctor determined by the type of medical service which has to be giving to the patient.