the opportunity of critically discussing the achievements and perspectives of the use of synchrotron radiation in biology and presenting them to a selected audience within the framework of an advanced school. From the very beginning we were encouraged in our initiative by many discussions with colleagues in the Rome area, who were later to become r.:.embers of the Scientific Committee of this Course. \oie were fully aware that ~y of the results obtained so far were of a pre­ liminary nature; we feIt, however, that they were sufficiently promising to justify this venture, which seemed particularly im­ portant in consideration of the increasing nur.:.ber of centers, where synchrotron radiation is becoming available.