The most frequent of the so-called vocational diseases "Attrition of brachial joints after working with compressed-air-tools" and "Change of the miner's menisci" have only a loose causal connection with the occupations they are named for: By far the majority of such workers are not affected-even though they handle compressed-air-tools, or do the labor of miners all during their working life. This study explains, that the cause for these diseases is not to be sought in any external influences typical for these activities but rather in some negative tendency of patient's tissue--a definite morbidity towards tissue-regression. Patients are born with this inclination, with, therefore, is not insurable. The conditions for public accident incurance are fulfilled only if work with compressed-air-tools or labour of miners aggravates these negative tendencies. The somewhat indirect causal connection between diseases and occupations, do bring up certain problems and make it rather difficult, to judge these "tissue-regressions as vocational diseases".