Historians of science have continuously searched forthe factors which determine why certain persons achieveproeminence in the area. Of prime importance, of course, istheir biological constitution; only persons with a given de-gree of intelligence can reach success. But there are manyadditional factors which are also important, including workdrive, persistence, as well as appropriate family and aca-demic environments.This combination of factors led to Israel Roisenberg’sbrilliant career, and the main events of his life are listed inTable 1. He was born in Porto Alegre on July 31, 1934,wherehelivedallhislife,exceptforvariedperiodsoftimeinSao Paulo and outside Brazil. After primary and secondaryeducation (the latter in a public school, Colegio Julio deCastilhos), he was approved in the Federal University of RioGrande do Sul (UFRGS) entrance exam for the BiologicalSciencesCareerin1958.Soonhedevelopedaninterestinre-search, and as a consequence I invited him to work as an un-dergraduate student in our laboratory. He graduated in 1961and soon afterwards received a contract as a Biologist atUFRGS. Our Post-Graduate Program was just starting at thetime, but he also immediately enrolled as a Ph.D. student.At the time I had just returned from the US, where Iwas enjoying a Post-Doctorate stay at the Department ofHumanGenetics,SchoolofMedicine,UniversityofMichi-gan in 1957/58, and was starting a research program in thearea which involved not only the population genetics ofAmerindians, but also medical genetics, due to the absenceof specialists, at the time, in this field. Several hemophiliapatients had looked for help in our Genetic Counseling Ser-vice, and therefore I suggested to Israel to work with thiscondition for his Doctoral Thesis.This was the beginning of a distinguished interest incoagulation and hemostatic disorders that lasted for all hislife. To learn the specific coagulation techniques he stayedfor some time at the Butantan Institute in Sao Paulo, underthe guidance of Gastao Rosenfeld, with whom he after-wards developed a strong friendship. The Ph.D. degree wasawarded in 1968, and he was the first student to obtain it inour Program.Newton E. Morton was at the time working in an ex-tensive program of research with northeastern Brazilians,and one of the logical choices was that Israel would go tohis laboratory for a Post-Doctorate stay. This occurred in1968/69, and there he obtained skills in the electronic pro-grams developed by Morton and performed field work inthe Pacific Islands. As a result, they published papers sum-marizingthegenealogicaldataobtainedinthePingelapandMokil attols (no. 5, List of Selected Publications) and theresults of his Ph.D. Thesis (6). They also examined aspectsof the population structure of Central and South AmericanAmerindians (4).Back in Brazil, he organized a highly successfulgroup of research in hemostasis and was actively engagedin undergraduate and graduate teaching. In relation to thelatter, 23 M.Sc. and 7 Ph.D. degrees were obtained underhis guidance from 1974 up to 2005.Along the years he made additional stays in the USA(1977) and Wales (1989), was the Coordinator of our Post-Graduate Program in Genetics and Molecular Biology foran extended period of time (1976-1992), President of theUFRGS Central Administration Post-Graduate SpecialChamber (1991/96), and received national recognition asPresident of the Brazilian Society of Genetics (1974-1976),as Member of the Council, Brazilian Society for the Ad-vancement of Science (SBPC) (1975/79), and was invitedto join the Advisory Committees of the Brazilian NationalCouncil for Research and Development (CNPq) in 1985-1989 and 2000/2001, as well as to the Rio Grande do SulState Foundation for the Development of Science(FAPERGS), from 1998 to 2001.