Ronald Fisher was probably the greatest statistician of the twentieth century. Gertrude Cox was an expert on experimental designs and an outstanding administrator and developer of statistical departments, first in North Carolina and then worldwide. These two associated in various roles for thirty years, on U.S. campuses and at international statistical associations. They were both founding members of the international Biometric Society in 1947. A major collision came in 1953, when Cox was editor of Biometrics. Fisher submitted an article critical of four contemporary statisticians and did not want to change it. Cox published his article and comments by the four, all in the same issue. There was deep underlying respect, however, and Fisher lectured and taught for Cox in North Carolina afterward. They continued to correspond, and to meet occasionally, until Fisher's death in 1962.