Roy Styring Dearstyne was born on September 11, 1889 in Rensselaer, New York. He received his B.S. degree in bacteriology from the University of Maryland in 1916. During World War I he was on detached duty with the United States Army and then worked as a bacteriologist for various public health departments from 1916 to 1921. In 1923, Dearstyne received his M.S. degree in poultry pathology from North Carolina State College and began his career as an N.C. State professor.

A member of the N.C. State faculty from 1922 until his retirement in 1955, Dearstyne served as an Associate Professor of Poultry Science, 1922-1930, and Professor and Head of the Poultry Science Department, 1930-1955. As a pathologist, he developed a testing procedure for controlling pullorum disease in poultry. He also wrote one of the first books in the nation about poultry diseases, was influential in organizing the North Carolina Hatchery Association and the North Carolina Poultry Council, and is considered to have been an instrumental to the development and expansion of North Carolina's poultry industry.

Dearstyne was a fellow in the National Poultry Science Association, as well as a member of the editorial staff of Poultry Science. He was also a member of a number of professional, scientific, and honor societies, including Alpha Zeta, Sigma Xi, Phi Kappa Phi, and the American Association for the Advancement of Science. After his retirement, Dearstyne became a consultant for the Farmer's Cooperative Exchange.

When Roy S. Dearstyne died on February 27, 1960, he was survived by his wife, the former Anna Rose Holly, and their son, Roy H. Dearstyne. The R. S. Dearstyne Memorial Loan Fund was established after his death to provide financial aid to poultry majors at N.C. State and a building named after him--the Dearstyne Avian Health Center--was built on N.C. State's West Campus in 1968.