Sea-squirt asthma is a typical allergic and occupational asthma caused by inhalation of sea-squirt substances. Therefore, the treatment and the prevention of this disease was emphasized on improvement in the occupational environment along with the specific hyposensitization therapy. Since in the last two to three years, there has been rapid and remarkable improvement in the environment and equipment of the working place, the comparison was done between the improvement of occupational environment and the occurrence of sea-squirt asthma before and after this change (viz. Feb. 1963 and Feb. 1968 respectively). Following results were obtained. 1) The complains of asthmatic symptoms were 45.8% for the former and 30.1% for the later. 2) The percentage of the severe asthma decreased from 64.5% in the former case to 20.0% of the later. 3) There were no patients who could work without asthmatic symptom in the former cases, but symptoms free in the 34 cases out of 90 patients in the later. 4) In the former cases, a tendency of almost all the mild illness becoming sever was noted, but there was no such tendency in the later.
