Objective. To examine the impact of online evidence retrieval on clinicians' decision-making confidence and to determine if this differs for experienced doctors and nurses. Methods. A sample of 44 doctors and 31 clinical nurse consultants (CNCs) answered 8 clinical scenarios (600 scenario answers) before and after the use of online evidence resources. Clinicians rated their confidence in scenario answers and in the evidence they found using the information system. Results. Prior to using online evidence, 37% of doctors and 18% of CNCs answered the scenarios correctly. These clinicians were more confident (56% very confident or confident) in their answers than those with incorrect (34%) answers. Doctors with incorrect answers prior to searching rated their confidence significantly higher than did nurses who were incorrect. After searching, both groups answered 50% of scenarios correctly. Clinicians with correct answers had greater confidence in the evidence found compared to those with incorrect answers. Doctors were more confident in evidence found confirming an initially correct answer than were nurses. More than 50% of clinicians who persisted with an incorrect answer after searching reported that they were confident or very confident in the evidence found. Clinicians who did not know scenario answers before searching placed equal confidence in evidence that led them to a correct or incorrect answer. Conclusions. The information obtained from an online evidence system influenced clinicians' confidence in their answers to the clinical scenarios. The relationship between confidence in answers and correctness is complex. Both existing knowledge and professional role were mediating factors. The finding that many clinicians placed confidence in information that led them to incorrect answers warrants further investigation.