It is observed that the working activity period has recently been decreasing in Poland; this applies to both the male and female populations. Since women constitute 48% of all workers employed in the national economy, this tendency may pose an important problem for the community and public health. The main information source for the absenteeism analysis are medical certificates which in Poland obligatorily document every instance of a sick-leave from work, irrespective of the length of sickness. A 15% random sample of all sickness certificates constitutes a database for the monitoring system of sickness absence. The lost time rate is the main parameter analysed by the system. In 1994 the rate of female sickness absence in Poland amounted to 25.1 days per one employee. In Poland the main causes of female sickness absence are: respiratory diseases--18% of all sickness absence (in the 16-19 age group--49%), and disorders of female genital tract and complications of pregnancy, childbirth and puerperium (17% of all sickness absence and 48% in the 20-29 age group). The most important chronic diseases that substantially contribute to the level of sickness absence include: musculoskeletal diseases (15%), diseases of the circulatory system (15%) and the nervous system and sense organs (11%). Over the period of 1990-1994 the highest rate of the female sickness absence related to gynecological diseases and pregnancy complications (mean annual increase--22%), and the musculoskeletal diseases (mean annual increase--10%).