The Bureau of Mines is conducting respirable dust surveys in metal and nonmetal mining operations to determine personal exposure levels and to define dust control problems requiring research and development. To date, four different underground mines (gold, lead- zinc, iron, and silica) have been sampled for specific occupations and for locations to determine airborne dust concentrations. In these studies, time-weighted, full-shift samples were taken for gravimetric analysis. All dust samples were taken with MESA- approved dust samplers. Flow rates of samplers were calibrated for 2.0 Liters per minute in the iron and silica mines and 1.7 Liters per minute in the lead-zinc and gold mines. Three types of dust- sampling packages were used: (1) personal, (2) machine mounted, and (3) area. Results show that dust concentrations vary significantly from mine to mine and within specific mining operations. At two underground mines (silica and lead-zinc) diesel exhaust emission contributed substantially to the dust concentrations. The gold mine had two locations (ore chute and ore bypass) that were above the threshold limit value (tlv) of 0.66 Mg/m3 as determined by the free- silica content.