With recent growth in class sizes and demands on staff time and resources, it is increasingly challenging to engage students in laboratory practical classes and give them constructive feedback on their work. We have developed an interactive web-based tool, eBiolabs, that supports students’ preparation for practicals by providing introductory material in the form of interactive animations, videos and quizzes. The tool also enables students to complete web-based, post-practical assessments on which they receive instant feedback on their knowledge and understanding. In 2010-11, eBiolabs was used to support the 13 practical classes in our first year Physiological Science BSc unit, taken by ~200 undergraduates. 95% of these students reported that accessing the site for the first time was easy and 91% said they felt more prepared for their first practical than if asked to read handbook notes. The average submission rate across all post-practical assessments was 94%, with an average score per assessment of 85%. In 2011-12, eBiolabs was extended to the second year of the BSc programme and to all first and second year units on the professional programmes (medicine, dentistry and veterinary science) on which physiology is taught. Prior to the introduction of eBiolabs, 91% of ~200 second year medical students reported spending less than 20min preparing for each practical class (with 66% spending almost no time on this). After its introduction, 72% of the same students reported that they spent at least 20min preparing (with 25% spending more than 1hr). Whereas only 30% of medical students had felt well-prepared for practical classes before the use of eBiolabs, that figure rose to 48% after using eBiolabs for one term (for 5 physiology practicals). Furthermore, the percentage of medical students reporting that feedback received on their post-practical work was clear and timely rose from 6% to 72%. In agreement with these data, 87% of first year dental students agreed that eBiolabs was useful in helping them prepare for practical classes and 67% agreed that the assessment feedback was useful for their learning (n = 63). The system has been well received on all courses and eBiolabs has brought other benefits to physiology practical teaching. Staff and demonstrators are able to access teaching material which allows better preparation for practicals, and student performance is easily accessible and clearly presented. With students being better prepared for practical classes they gain more from the laboratory experience and can engage fully with the physiological principles behind experiments rather than focusing on operational/technical issues. eBiolabs has become an integral part of physiology teaching at the University of Bristol as a vital tool that allows student engagement in practical classes and is accessible for staff and students alike.