The possibilities of screening workers for genetic traits that may place them at unusual risk in the work environment or evaluating genetic material from workers for evidence of the adverse effects of occupational exposures were considered. The former approach was called genetic screening, and the latter, genetic monitoring. A brief review considered selected genetic variants and associated diseases such as red blood cell traits and predisposure to acute hemolytic anemia for persons with glucose-6-dehydrogenase deficiency, the occurrence of sickle cell anemia in individuals having a specific change in the amino acid structure of the peptide chains of hemoglobin, and the occurrence of thalassemia major due to a genetic defect in the rate of hemoglobin synthesis. Genetic traits associated with lung diseases include increased aryl- hydrocarbon-hydrolase activity associated with bronchogenic carcinoma, and alpha-1-antitrypsin deficiency associated with obstructive pulmonary disease, particularly emphysema. Other selected metabolic polymorphisms associated with diseases included slow acetylator phenotype, microsomal oxidizing systems, and paraoxonase deficiency. Genetic monitoring of workers would search for cytogenetic indicators, effects of exposures on sperm, the presence of oncogenes, and noncytogenetic indicators. With only a few exceptions, researchers have failed to adequately demonstrate the practical relevance of genetic polymorphism to the health of workers. Current research has leaned in the direction of recombinant DNA based testing, and interactions between the gene and environment. Ethical and legal issues were also discussed.