The need for determining the potential genotoxic effects of longterm exposure to complex workplace environment has been widely accepted (see IARC 1984, ICPEMC committee 1985, ICEM 1989) and a number of techniques have been adopted for the purpose (for review see Anderson 1988). Screening for chromosomal aberrations in cultured lymphocytes is now an accepted method for monitoring populations exposed to various chemicals, singly or in mixtures (Forni 1983, Galloway et al. 1986, Sorsa et al. 1982, 1983). Such studies are of particular importance in India, where industrialisation has progressed rapidly in certain belts during the past four decades. The present study was undertaken on groups of workers in metal industries, exposed directly and indirectly to complex environmental work conditions, using chromosomal aberrations as the endpoint for monitoring. Individuals were matched with respect to age, sex, nutritional status and addiction.