Mannequin and computer-based simulators are useful for the practice of patient management, physical procedures, and competency. However, they are ineffective in teaching clinical medicine. StepStone Interactive Medical Software (SS) is a web-based medical learning modality that provides the user with a highly focused set of evaluative and interventional tasks to treat memorable virtual patients in a visual case-based format. To determine whether the SS learning modality is superior to traditional lecture format in medical student learning and retention. After Institutional Review Board (IRB) approval was obtained and the consents were signed, 30 third-year medical students were assigned randomly to 2 groups of 15 students each: The control group received two 30-minute PowerPoint lectures (Microsoft Corporation, Redmond, Washington) about torsades de pointes (TdP) and pulseless electrical activity (PEA), and the SS group was given 1 hour to review 2 SS cases teaching TdP and PEA. A preintervention test was given to assess their baseline knowledge. An immediate postintervention test was given to both groups. Twenty-two days later, a long-term retention test was administered. The results were analyzed using a Student t test for continuous variables. The mean scores for the preintervention test in the control and SS groups were 44.9 ± 3% and 44.1 ± 2%, respectively (p = 0.41). The mean scores for the postintervention test in the control and SS groups were 61.7 ± 2% and 86.7 ± 2%, respectively (p < 0.001). Improvement from baseline knowledge was calculated, and the mean improvement was 16.8 ± 3% in the control group and 42.5 ± 2% in the SS group (p < 0.001). The long-term retention test revealed the mean scores of 55.8 ± 3% in the control group and 70.1 ± 3% in the SS group (p < 0.001). Long-term improvement from baseline knowledge was calculated and the control group improved by 10.9 ± 4%, whereas the SS group improved by 26 ± 3% (p = 0.002). The SS learning modality demonstrated a significant improvement in student learning retention compared to traditional didactic lecture format. SS is an effective web-based medical education tool.