Determination of total Ca in the Lung Tissue of Rats by FAAS was described, with a mixed microemulsion consisting of sodium dodecyl sulfate, N-dodecyl, N-dimethyl benzol ammonium bromide and nonyl phenol polyethyeneoxy ether. Comparing the result of the microemulsion FAAS with that of solution FAAS showed that the former was better than the latter in sensitivity, precision, selectivity and linearity of the calibration curve, with a detection limit of 1.92 microg x cm(-3), relative standard deviation of 1.92% (n = 10) and linear regressive coefficient of 0.9998 of the calibration curve over 0-20 microg x cm(-3) calcium. The method was applied to determine calcium amount in the lung tissue of rats, and the results were in accordance with those odtained by the conventional solution FAAS, in which a sample was reduced to ashes at a high temperature.