The article deals with results obtained in hygienic evaluation of production and application of new monocrystalline compounds based on cesium, sodium, iodine, lead, scandium, fluorine. The evaluation covered work conditions and health state of those engaged into production of monocrystalline compounds, revealed the main occupational hazards. The experiments determined fundamental toxicometric parameters, studied characteristics of general toxic and specific effects induced by lead fluoride and cesium iodine. The results formed basis for sanitary measures, establishment of MACs for 4 monocrystalline compounds in the air of workplace.