The economic impact of some future biological nitrogen fixation technologies are estimated using AGSIM, a dynamic, partial equilibrium, econometric model of the U.S. agricultural sector. Five separate scenarios were modeled: (1) legumes fix more nitrogen, (2) legumes fix more nitrogen with an increase in legumes yields of 10 percent, (3) nitrogen fertilization requirements on all crops are reduced 50 percent with no yield changes, (4) total elimination of nitrogen fertilization and (5) total elimination of nitrogen fertilization and non-legume yields decrease 10 percent. Results indicate that biological nitrogen fixation technologies have a high value to society. Increasing the efficiency of legumes to fix nitrogen may have an annual benefit of $1,067 million while decreasing nitrogen fertilization by 1,706 thousand tons. Total elimination of nitrogen fertilization of the crops has an annual benefit of $4,484 million.