He studied environmental engineering and biology at the University of Oklahoma, and received a degree from Johns Hopkins University.
His scientific career included work in parasitology, field studies of whales in the Canadian Arctic, study of the greenhouse effect, and the collection of documents relating to agriculture in Florida.
Haldeman published about 10 novels and over 100 short stories, beginning with "Garden of Eden" in the December 1971 Fantastic. He is notable for writing science fiction with sports themes; "Home Team Advantage", first appearing in IASFM in 1977 has been anthologized a number of times. "High Steel", a 1982 story co-authored with Jack Dann, was a Nebula Award nominee.
He was married to writer Barbara Delaplace.