For those who are eligible, taking part in research studies offers several benefits: Getting actively involved in their own health care Having access to investigative research treatments Having access to study-related care for the condition being studied Helping others by contributing to medical research It is important to test drugs and medical products in the people they are meant to help. It is also important to conduct research in a variety of people because different people may respond differently to treatments.  For each research study, researchers develop eligibility criteria, such as age, gender, previous treatment history, and other medical conditions. Not everyone who applies for a research study will be accepted. Volunteers may be excluded based on the eligibility criteria and/or the number of participants needed by the researchers.