Jean O. Lanjouw, 43, an economist whose research on affordable medicines in developing countries contributed to public policy, died of renal cell cancer Nov. 1 at her home in Washington.

Dr. Lanjouw combined her expertise in intellectual property rights and her concern for reducing world poverty to advocate for a system that would give Third World countries access to drugs at the lowest cost while protecting patents of pharmaceutical firms and incentives for medical innovation.

Dr. Lanjouw was a noted scholar, professor and author whose work had begun to gain resonance in the past few years in the debate over patent protection for drug manufacturers in developing countries.

A column in The Washington Post in June said that Dr. Lanjouw's proposal to make drugs that have been invented for rich countries available to poor ones was not getting enough attention.

"Jean Lanjouw advanced a solution to the heart-pill problem," Sebastian Mallaby wrote. "The idea would cost nothing: It merely involves drug companies giving up patent protection for heart pills and similar medicines in the poor world. Since poor countries buy almost none of these medicines anyway, giving up patent rights in those markets doesn't hurt the drug firms. But it would mean that cheap generic versions of these medicines could be distributed to poor consumers."

Dr. Lanjouw also had done work on property rights in developing countries, examining the role of land titles in urban squatter communities such as Guayaquil, Ecuador. She and her husband, a researcher at the World Bank, also were creating "poverty maps," a statistical methodology for viewing poverty at the neighborhood or village level.

She was on sabbatical as an associate professor of economics in the Department of Agricultural and Resource Economics at the University of California, Berkeley. Dr. Lanjouw was passionate about turning the ideas in academic research into reality, said Berk Ozler of the Development Research Group at the World Bank.

"She traveled tirelessly from India to Switzerland, Berkeley to the Research Triangle, and to the Congress in Washington, D.C., to promote better access to generic drugs in poor countries."

Known as Jenny, she was born in Seattle and grew up in Oxford, Ohio, where she graduated summa cum laude in mathematics and economics from Miami University.

While attending a master's program in economics at the Delhi School of Economics in India in the mid-1980s, her interest in developing countries took hold. She later received a master's degree (1987) and doctorate (1992) in economics from the London School of Economics and Political Science.

She moved to Washington in 1992 and commuted to her position as an economics professor at Yale University.

She had fellowships at the Brookings Institution, the Center for Global Development and the National Bureau of Economic Research.

Her papers were published in numerous academic journals, and she consulted for the World Bank, the U.N. Development Program and statistical organizations in South Africa and Brazil.

Survivors include her husband, Peter F. Lanjouw, and two children, Else Lanjouw and Max Lanjouw, all of Washington; her parents, Joann Olson and Bruce Olson of Oxford; and a brother, Eric Olson of Oxford.

Jean O. Lanjouw endorsed allowing firms in poor countries to produce patented drugs.