During her career as insurance commissioner, Ms. Vaughn served in a variety of positions with the National Association of Insurance Commissioners, including president in 2002.

In recent years, she has been particularly active in the NAIC's regulatory modernization efforts, international affairs and coordination with banking and securities regulators, both in the United States and internationally.

She also led development of NAIC's market response to 9/11, including work with Congress and the U.S. Treasury on the federal Terrorism Risk Insurance Act of 2002.

An agency staff official said Ms. Vaughn was unavailable for comment. He said the governor is likely to name an acting successor to Ms. Vaughn shortly.

Besides overseeing all insurance business transacted in Iowa, Ms. Vaughn was regulator of securities activities and in charge of regulating miscellaneous industries including funeral homes and cemeteries.

Ms. Vaughn is leaving her post just several weeks after the death of her father, Emmett Vaughn, the J.E. Partington professor of insurance at the University of Iowa.

Mr. Vaughn died Oct. 22 while on vacation. Mr. Vaughn joined the UI faculty in 1963. Since then, he served in a variety of positions, including director of the UI's Institute for Insurance Education and Research, associate dean and interim dean in the College of Business Administration, and dean of the Division of Continuing Education.

Mr. Vaughan wrote "Fundamentals of Risk and Insurance," a textbook in its ninth edition. His 15 books have been translated into Chinese, German, Italian, Japanese, Korean and Serbo Croatian.