Objectives: The aim of the study was to evaluate the effectiveness of two brief preventive stress reduction programs - a cognitive focused program and a combined intervention of physical exercise and relaxation - on sickness absence in stressed and non-stressed employees working in various jobs in a telecom company. Methods: The study was designed as an a priori randomized trial and the follow-up period for sickness absence was 1 year. Sickness absence data of 242 employees were analyzed with respect to spells of sickness (frequency, incidence rate), days (length, duration) and time between intervention and first subsequent absent spell. Results: For stressed employees this study suggests that the illness burden represented by absenteeism is not affected by the interventions. There is no substantial difference in effectiveness between the cognitive and physical interventions. However, in comparison with the physical intervention the cognitive intervention decreases the period between the intervention and the first recurrence of a sick leave period with 144 days (marginal significant). Conclusion: The illness burden represented by absenteeism is effected in detail but not substantially by the interventions. © Springer-Verlag 2006.