Dr. Saul Krugman, a longtime head of pediatrics at the New York University School of Medicine and a leader in the development of vaccines against measles, rubella and hepatitis, died on Thursday at Broward General Hospital in Fort Lauderdale, Fla. He was 84 and had lived in Fort Lauderdale since his retirement in 1991 as professor of pediatrics at New York University Medical Center.

The cause was a cerebral hemorrhage, a spokesman for the medical center in New York said.

Dr. Krugman's association with N.Y.U. lasted 47 years. He was chairman of the department of pediatrics from 1960 to 1975, a period during which he also directed the pediatric service at Bellevue Hospital. He established one of the country's first comprehensive children's health clinics, setting a pattern for medical centers elsewhere in the country.

He and his co-workers evaluated newly developed vaccines against polio, measles, rubella and hepatitis B. In his crowning achievement, he unraveled the mysteries of viral hepatitis and helped defeat that family of debilitating diseases.

Dr. Krugman, the author of well over 200 scientific papers, received many honors in this country and abroad, including a medical research award for public service in 1983 from the Albert and Mary Lasker Foundation. Its citation said that Dr. Krugman had provided "critically important studies of hepatitis, rubella and measles." It singled out his pivotal role in creating a vaccine against the hepatitis B virus. That insidious microscopic organism caused liver disease for an estimated 300 million people around the world and contributed significantly to liver cancer.