This study was carried out from June, 20, to October 22, 1988, for the purpose of researching on the complaint ratio of Respiratory symptoms of the dental laboratory technicians in Seoul. In this study, aiming to find out complaint ratio of respiratory symptoms of the dental laboratory, SNU-81-AL were applied, at random, to 193 dental laboratory technicians at 39 dental laboratories, as the research group, and to 178 clinical laboratory technicians at 10 general hospitals, as the control group, and above two groups were compared with each other. The following results were obtained from this research. 1. The quantity of respirable dust under 5$\mu$m measured at the dental laborartories was, on an average as well, 5$mg/m^3$-minimum 1.56$mg/m^3$), and the density of CO was, on an average as well, 5.0ppm(Mx 7.0-Mn 3.0). 2. The complaint ratio of five main respiratory symptoms(cough, phlegm, wheezing, nasal catarrh & cold, breathlessness) was, on an average, 44.3% at the dental laboratory technicians, phlegm was the major symptom complained by the greatest number of the technicians. 22.4% of the clinical laboratory technicians complained above 5 main respiratory symptoms, nassal catarrh & cold was the mostly complained symptoms among them. There showed a consideraly significant difference at the complaint ratio between the above 2 occupations(P<0.005). 3. There showed no paticular significant difference between male and female, at the complaint ratio of the dental laboratory technicians. However, there showed a considerable significant difference according to their sexuality, in case of the clinical laboratory technicians. 4. Considered from th view point of age, the highest age group was 20-29 with its average 48.5%, in case of dental laboratory technicians. The highest age group among the clinical laboratory technicians was over 40 age with its 28.7%. There showed no particular significant differences between to tow occupations. 5. Considered from the view point of work period, the highest work period group was 0-3 years with average 47.8%, in case of dental laboratory The highest work period group among the clinical laboratory technicians was 16 years with its 25.2%. There showed no particuar significant differences between the two occupations. 6. Considered from the view point of smoking, phlegm was complained by much more smokers than non-smokers, in both occupations. In case of non-smokers, many complained about nassal catarrh & cold. There showed no particular significant differences between the smokers and the non-smokers.