This review discusses the literature from January 1964 to January 2000 concerning the sources of hydrogen sulfide, including the human body, natural, biogenic, and anthropogenic sources. The scope of this search did not include literature on the health effects of hydrogen sulfide. Our objective was to identify measured concentrations of hydrogen sulfide that have been reported in the literature. For all studies, we evaluated the analytical techniques used to measure hydrogen sulfide. Prior to commencing the current study, our preliminary field measurements indicated that biogenic and other natural sources far exceed industrial contributions. In a rural community on the Central Coast of California, we found average ambient concentrations of approximately 2.0 ppby, three times the USEPA RfC of 0.7 ppb. Human breath measurements of area residents averaged 48 ppby. This study was completed to support one of the largest community monitoring plans ever undertaken for a petroleum remediation site. We conducted the hydrogen sulfide literature review as the first step in a program proposed to the American Petroleum Institute in September 1999. The objectives of the program as a whole are to determine if: (1) low ambient concentrations are ubiquitous and not restricted to downwind of industrial sources and (2) natural and biogenic sources predominate. The literature review was conducted to determine what is currently known about concentrations of hydrogen sulfide in the human body and the environment. The results of this review will serve to establish a baseline for the next phase of the project, which involves measurements of human and ambient levels of hydrogen sulfide.