Frank Lahey was born in Haverhill, Massachusetts, on June 1st. He was an only child, and his father was a wealthy bridge contractor. He attended Haverhill High School and went from there to the Harvard Medical School, from which he received the M.D. in 1904. After he served as intern and house surgeon in the Long Island Hospital (1904-1905) and as surgeon in the Boston City Hospital (1905-1907), Lahey became resident surgeon of the Haymarket Square Relief Station (1908). He was on the surgical faculty of the Harvard Medical School as an instructor from 1908 to 1909 and 1912 to 1915. From 1913 to 1917, he served as Assistant Professor of Surgery at the Tufts Medical School.

During World War I, Lahey served as director of surgery of Evacuation Hospital No. 30, which was part of the U.S. Army Expeditionary Force. His extensive experience as a military surgeon strengthened his resolve that asepsis, antisepsis, and anesthesia had created a new surgery, which was best performed and refined by teams of surgical specialists. After his return from military service, he began practice in Boston and started a private hospital, which, through the strength of his experiences as an army surgeon, developed into the Lahey Clinic.

Although named to an unprecedented joint chair in surgery at Tufts and Harvard (1923-1924), he resigned within a year to devote himself fully to the Lahey Clinic. Lahey believed that surgery could be done best by teams of specialists, who would share advanced techniques, including the division of complilcated surgery. Lahey's work at his Clinic greatly reduced the high mortality rate of thyroid surgery and pioneered total removal of the stomach and colon.

Regarded as one of America's greatest teachers of surgery, Lahey exerted a strong educational influence. He stressed that the entire surgical team deserved credit for all achievements and believed that "organized surgery" gave invaluable experience for young specialists.