I highly recommend using this book during your internal medicine rotation. The questions are shorter than those on the actual shelf exam, but they require the same thought process. On the shelf, the questions are less focused on "what disease does this patient have?" and instead involve choosing the appropriate diagnostic test or treatment. The same can be said of the questions in MKSAP 3. Another nice feature is that the book comes with a CD with all of the questions. This allows you to keep better track of your progress and to take the questions in a random mode, rather than just subject-based. Besides doing the questions themselves, it is also important to read through the answer explanations, which are excellent. Overall, a great investment!