To evaluate the effect of industrial noise on pregnant rats, 10 mature female rats (Wistar, Wt.250+30 g) were chosen and kept in cages by a ratio of 2:1 with male rats. Vagina smear were made the next morning and the pregnance-confirmed females were randomly divided into 2 groups, exposure and control. The exposure group started to be exposed around the clock for 9 d on end to a stable 98 dB(A) industrial noise from the third of their pregnancy. They were killed on the 20th day of their pregnancy and cut open at the belly to take out the fetus, for which registered were the numbers of implantation, living fetus, dead fetus and absorbed fetus as well as the development of corpus luteum and fetus. Their soft tissue was eliminated, fixed, stained and made transparent for the examination of their skeleton. The results were shown as follows: The rate of absorbed fetus was 12 6 in exposure group and 0% in control group, revealing a significant difference (P<0 05); the body length, tail length and body weight were less in exposure group than in control group (P<0 01); the rate of delayed ossification was higher in exposure group than in control group, presenting a marked variance (P<0 01); and the lack of occipital bone was found in 2 exposed cases, but not in control group. All the above suggested that industrial noise was harmful for the fetus to develop.