Indiana University's Premedical: Health Professions and Prelaw Center (HPPLC) Guidebook has a section regarding research experience. They state that while research experience is not a requirement for admission to their medical school, it can certainly enhance your preparation for a career in the medical field. They further describe how participating in research can also help you better understand what you learn in your coursework. Since the science you learn in the classroom comes from research, the more you understand the process of formulating and investigating hypotheses, the more enhanced your learning experience will be.
IU School of Medicine is transparent on its website, saying that even though research experience is not a technical requirement for admission, it is extremely important to gain significant research experience, as your research potential will be weighted heavily in decisions on admission to medical school. Describe your research experience, and be sure your letters of recommendation from your professors highlight your research experience and potential.