Observation and analysis of sickness absenteeism, its morbidity causes, range and trends in certain periods of time, help to identify major health problems in the working population and the dynamic of changes. They also permit to anticipate the consequences reflected in permanent work disability. Certificates recording temporary work disability serve as a reference source for the analysis. The material under study comes from the national sickness absenteeism data base developed and managed by the Nofer Institute of Occupational Medicine in Lodz. It covers a 15-percent random sample of those cards. During the last decade, temporary work disability showed a rapidly growing tendency. During the years 1985-1994 mean annual rate of sickness absenteeism growth accounted for 6.4%, and since 1990 this rate has evidently increased reaching 10% per year. The rate of sickness absenteeism growth was considerably higher among males (9.8%) than among females (4.1%). The highest mean annual rates of growth were noted in absenteeism caused by diseases of the musculoskeletal system (33%--males; 15%--females), the nervous system (18%--males; 4% females) and the circulatory system (12% in general) including arterial hypertension (52%--males; 17% females). A differentiated trend in work disability due to individual disease categories observed during the analysed decade was responsible for changes in the structure of sick absenteeism noted in the same period. Thus, sickness absenteeism because of diseases of the respiratory system has decreased while diseases of the musculoskeletal system have contributed to its increase (at present they account for 18.2% in males and 15.4% in females), the same applies to diseases of the nervous system (17.2% in males) and to gynecological diseases (17.1% of female absenteeism). During the past five years a high dynamics of sickness absenteeism growth can be mostly attributed to a modified system of sickness allowances as well as to social and economic transformations, restructuring of industry and an increased unemployment in our country.