The need for ever better evaluation of the workforce's workability in a business, as well as the study on absenteeism for medical reasons is an important challenge for the Occupational Health Service. Aim: The aim of the present study is to examine whether there is a correlation between the Workability of employees and their absenteeism for medical reasons. Material - Method: The study took place in the period 2003-2006, on 98 accounted filled-in questionnaires, from a sample of employees in an industrial unit in the district of Athens. Primarily, using the original questionnaire that has been developed by the FIOH, an evaluation of the Workability Index (WAI) was carried out on all of the 98 cases. Absenteeism form medical reasons was controlled for the tree years 2003-2006 on each of 98 employees who participated in the study. For the statistical analysis it was used the statistical program SPSS 13 and the statistical methods tests x2, t-test and one way analysis of variance (One-way AN.O.VA.). Results: The analysis of the questionnaires showed that 48 employees had grade of WAI excellent, 42 had WAI Good, 7 had WAI Moderate and only 1 employee had WAI Poor. Following was the study of absenteeism for medical reasons. The Average days of absence from work due to medical reasons, was founded to be for each WAI category: WAI Excellent: 4.5 days per employee, WAI Good: 10.1 days per employee, WAI Moderate & Poor: 18. 8 days per employee. The statistical analysis proves that there is a high statistical significance correlation to absenteeism for medical reasons amongst the categories of WAI. Additionally, it is proved that there is a high statistical importance correlation to absenteeism for medical reasons amongst the categories of WAI (p<0.014). Conclusions: It is deducted that WAI have a high statistical significance correlation to absenteeism for medical reasons. By given the present aforementioned, WAI can be a useful tool for the Occupational Health Service.