Nursing as a health-service has a long tradition, nursing research however, a relatively short history. Florence Nightingale was the first to publish about nursing research in the year 1858. Since Nightingale, the need to study and improve the efficacy and efficiency of nursing has steadily increased. More than ever before, society needs nursing based on scientific knowledge and not just on unchallenged rituals and traditions. This scientific knowledge base can be acquired by clinical research. Within multidisciplinary clinical research it is necessary to focus on nursing's unique function. Virginia Henderson (1955) and Dorothea Orem (1959) have clearly explicated this function. Designs for clinical nursing research can be (quasi-) experimental, correlational or descriptive. Descriptive research can be qualitative or quantitative. Effects of nursing interventions on decrease of self-care problems and improvement of self-care capability and behaviors, should be investigated by experimental or quasi-experimental studies. Some examples of clinical nursing research are given. The first example demonstrates the effect of quantity and quality of nursing staff on patient's capabilities for hygiene self-care. The second example explicates the relation between self-care and quality of life with breast-cancer patients under chemotherapy treatment. The last example shows the effect of diabetes education on self-care behaviour and metabolic control. The examples given demonstrate the importance of clinical research focused on nursing's unique function. In order to accomplish this, programs of research are needed as well as close co-operation with nursing services, physicians and hospitals. Only when research findings are discussed and implemented in multidisciplinary teams, nursing will become more evidence-based.