The increase in the new cases of occupational disease reported in Finland in 1977-1983 has been analyzed. First, the technical nature of the concept of occupational disease as used in the context of compensation insurance is described and a disability grading for the severity of occupational diseases is presented. It is then shown, with the use of a stratified probability sample, that the fraction of compensated cases has remained roughly constant during the study period. However, evidence is presented indicating that the severity of the cases compensated in 1977-1983 has, on the average, decreased.