President Bush designated the National Cancer Institute's director, Dr. Andrew von Eschenbach, to be the agency's new acting commissioner.
Crawford's resignation came just two months after the Senate, in a long-delayed move, elevated the longtime agency deputy and acting commissioner to the top job.
His three-year tenure at FDA was marked by increasing criticism, as the painkiller Vioxx (search) was pulled off the market for safety problems, recalls of malfunctioning heart devices mounted and controversy grew over wider access to emergency contraception.
His resignation came just two months after the Senate, in a long-delayed move, elevated the longtime agency deputy and acting commissioner to the top job.
Last month, morale at the agency plummeted when Crawford indefinitely postponed nonprescription sales of morning-after contraception over the objections of staff scientists who had declared the pill safe. FDA's women's health chief resigned.
Still, Crawford's resignation, effective immediately, was a surprise. An affable veterinarian who specialized in food safety, he was elevated by President Bush from acting commissioner to the full job in part because his experience was deemed important as the FDA attempted to better safeguard the food supply against bioterrorism. Crawford gave a speech Monday in Washington during which he betrayed no sign he was planning to leave, instead discussing upcoming FDA policy on the safety of cloned beef.
Health and Human Services Secretary Mike Leavitt (search) accepted Crawford's resignation "with sadness," said department spokeswoman Christina Pearson. "We thank him for his service and wish him well."
Asked if he was forced to resign, Pearson declined further comment, calling it a personnel issue.
Critics welcomed Crawford's departure.
"Lester Crawford's leadership at FDA since 2002 has been both tepid and passive," said Sen. Barbara Mikulski (search), D-Md. She called his resignation "a move toward reforming FDA."
Crawford, who had worked at the agency on four separate occasions over 30 years, cited among his accomplishments new steps to improve drug safety, efforts to speed drug development and the bringing of more funding to the cash-strapped agency through manufacturer-paid fees.
"I also must thank the extraordinary people of FDA for the honor of having served with them," Crawford wrote in a memo to his staff Friday. "They have made public service a joy and a pleasure as we worked together to accomplish great things for public health."
Officials did not immediately name an acting director of FDA, or a new candidate for the top post.