Lectures in Immunochemistry is a compilation of lectures that would probably never have been put together but for an unusual combination of circumstances. The book includes six lectures given at the behest of Professor Tornio Ogata, Professor of Serology in the Faculty of Medicine at the University of Tokyo. The six lectures were conducted before the Faculty during the period from September 26 to October 6, 1955. No attempt was made to give a course in immunochemistry, since much of the subject was being covered in Professor Ogata's own course in serology. It seemed more profitable, both for the lecturer and his listeners, to select a limited number of topics and to discuss their historical development under the impact of the introduction of quantitative micromethods conforming to the rigorous criteria of analytical chemistry. At the suggestion of Professor Takeo Tamiya, material was included to show how and why certain topics and substances were chosen for the research to be described and discussed. Although the resulting six lectures present an incomplete coverage of the field, they at least bring together a number of scattered fragments into a whole, unified by an experimental approach to the various problems, and by the solution of those problems through the application of quantitative analytical micromethods.