In order to evaluate the mutagenic effects of extractable indoor air pollutants (organic matters), we measured the mutagenic activities by sensitive microsuspension Ames test using new tester strains (YG 1024 and YG 1029). And additionally to evaluate the mutagenic effects on vital cell, we examined the frequencies of micronucleus appearing in lymphocytes from dye handling workers and controls. This study was conducted from Jan. toMay, 1995. The extractable indoor air pollutants were collected by low volume air sampler in a general office room and 3 of dye handling factories. And the environment of general office room divided into 3 different groups according to the type of room heaters. To determine the frequencies of micronucleus appearing in lymphocytes, we sampled peripheral venous blood from 20 of dye handling workers and 20 of controls, and cultured, and then examined the lymphocytes. The results obtained were as follows: 1. The indirect mutagenic activities of extractable organic matters from suspended particulates colleced in a general office room were higher than the direct one. 2. The strain YG 1024 was the most sensitive, and the increasing order of test strainsthat showed higher number of revertant were YG 1024, YG 1029, TA 100, and TA 98. 3. In the general office room, the room using kerosene heater showed the highest mutagenecity, and the next was buthan gas heater, and non-heating room in order. 4. The mutagenic effects of suspended particulates in::dye handling factories on the strain YG 1024 was 1.2 times higher than YG 1029. 5. The frequencies of micronucleus appearing in lymphocyte of the circulating blood of dye handling workers and the control were 5.65+/-2.97% and 4.65+/-0.97%, respectively. And the difference was statistically significant.