Data have been compiled from the available world literature on the accumulation and bioconcentration of selected toxic trace metals in human hair and nails and other mammalian hair, fur, nails, claws, and hoofs. The toxic trace metals and metalloids include antimony, arsenic, boron, cadmium, chromium, cobalt, copper, lead, mercury, nickel, selenium, tin, and vanadium. These have been tabulated by toxic metal, geographic area, subjects, sex, age, exposure gradient, analyses in ppm, and authority, from over 400 references. This compilation should provide background baseline reference information to help evaluate the usefulness of tissues for biological monitoring, and to help in the establishment of national or worldwide biological monitoring systems and networks. The various uses of hair for biological monitoring are reviewed for correlating with environmental exposure gradients, diseases associated with excesses and deficiencies, geographic distribution, and historic trends. The advantages and disadvantages of using hair for biological monitoring are discussed. It appears to be that if hair and nail samples are collected, cleaned, and analyzed properly with the best analytical methods under controlled conditions by experienced personnel, the data are valid. Human hair and nails have been found to be meaningful and representative tissues for biological monitoring for most of these toxic metals.