The development and use of mobile facilities for the analysis of occupational hazards to reproduction was described. The researchers used mobile laboratory facilities with which they could evaluate fresh semen samples in the field for a wide variety of semen characteristics in addition to concentration and morphology. Semen samples were produced at home by the workers and brought to the mobile laboratory in a thermos container within 1 hour of collection. Initial evaluation conducted in the field consisted of: recording semen volume, pH, color, turbidity, viability, and sperm counts; slide preparation; video recordings; and preservation of seminal plasma. Morphologic and morphometric studies as well as computer analyses of video tapes were conducted at the in house laboratories. These methods were applied to a study of workers occupationally exposed to ethylene-dibromide (106934) in the papaya fumigation industry. Six plants where 75 male workers were employed were investigated. Discussion of participation rates, sample collection, sample size, and the results were included. The authors conclude that the results of semen analysis studies can be used in epidemiological studies of occupational hazards to reproduction.