SINCE last August there have been reports in the Press of a crisis among biologists in the U.S.S.R. The crisis culminated in a decree from the Presidium of the Academy of Sciences, published on August 27. This decree dismisses a number of prominent biologists from their posts, closes two famous laboratories, and removes orthodox geneticists from committees and editorial boards of the Academy. The Press reports have not been complete or objective ; and the only full accounts of the crisis have been in the Russian language. British biologists will be grateful, therefore, to the Commonwealth Bureau of Plant Breeding and Genetics, which has now brought out a summary1 of the conference which led to the crisis, from articles in Pravda over the first three Weeks of August. At the same time, an English version of Lysenko's speech at this conference has been published under the auspices of the Society for Cultural Relations with the Soviet Union2. These two documents, together with an essay published by the Bureau of Plant Breeding two years ago3, and an illustrated account of Lysenko's experiments4, provide the British reader with adequate data to interpret the recent decree of the Academy of Science.