Background: there is too much information available related to medical research. It is highly necessary to teach undergraduates, postgraduates, and nursing and medical students 'how to build' a correct medical question starting from patients, and also how to elaborate research questions. It is imperative to consider the support that nursing and medical care means to patients, family and community.

Objectives: to analyze the best study designs to find evidence-based answers for questions related to patients' care and its success.

Methods: a literature review, starting from randomized clinical trials. We tailored search strategies for different databases reviewed. PubMed, Clinical Queries, Cochrane Library, Epistemonikos Clinical Key (Elsevier), EBSCO and others.

Results: we analyzed the research designs according to research questions. We considered the advantages and disadvantages of each design, looking for the best to provide and support nursing and medical care.

Conclusions: through the analysis of different research designs, we found the best and most reliable evidence in systematic reviews. They are no doubt, the best support to reach an informed and evidence-based answer to solve any nursing or medical issue. It is necessary to review different sources so as to include all the published and unpublished, evidence, where possible.

Patient or healthcare consumer involvement: patients should be informed about nursing and medical care. The support provided by the evidence of systematic reviews gives the patient better information about their care.