This book has correct answers and explanatory text with references for the 150 sample test questions on a CD-ROM given out by the National Board of Medical Examiners for preparation for Step 2 of the United States Medical Licensure Examination USMLE. The book consists mainly of a brief explanatory review of the subject of the test item. Finally, each explanation contains specific references to appropriate sections of standard textbooks for further review of the topic. This book is designed for review for the USMLE, Step 2.