A Level I materials balance was performed on benzene. Data are reported for benzene production from petroleum by four processes (catalytic reformation, toluene dealkylation, toluene disproportionation, and isolation from pyrolysis gasoline) and for production from coal during coking. Amounts of benzene consumed for the synthesis of nine direct derivatives (ethylbenzene, cumene, cyclohexane, nitrobenzene, maleic anhydride, mono- and dichlorobenzenes, alkylbenzenes, anthraquinone, and biphenyl) and exports are presented. These uses constitute approximately 93 percent of total benzene usage. Non-consumptive uses (solvents and inventory changes) are also tabulated. Emissions due to each of the above processes are reported or estimated where possible. In addition, emissions due to indirect production (refinery operation, coke oven operations, oil spills, non-ferrous metals manufacturing, ore mining, wood processing, coal mining, and two phases of the textle industry) are presented. Production of benzene as a component of gasoline and emissions due to gasoline use are estimated. Locations of sites with high densities of benzene producers and users are tabulated: the major 'hotspots' are Houston/Galveston, Texas; Corpus Christi, Texas; Beaumont/Port Arthur, Texas; and Puerto Rico. The uncertainty ranges of all numbers used or derived in this report are evaluated and general recommendations are presented. The results of the report are summarized in two figures: the Environmental Flow Diagram for benzene in Appendix A, and the Materials Balance Diagram in the Executive Summary.