Objective: The prevalence of chronic asthma has tripled during last two decades in Finland, but overall costs of disease management have not increased and patient level costs have decreased significantly. We analyzed with comprehensive time series all expenditures as well as the effectiveness of interventions such as the national action program (1994-2004) and development of pharmacotherapy. Methods: Finnish registry based data from 1987 to 2005 was combined to evaluate all costs of asthma. These included comprehensive health care costs, sick-leave compensations, disability pensions, and loss of productivity; all converted to 2004 euros. Several scenarios were constructed to identify the important changes in care processes and cost drivers during this period. Results: The number of patients with valid special reimbursement for asthma medication increased significantly (83,000 to 216,000) during the observation period yet the overall expenditure of care remained at the level of 1987, at €240 million. Cost of medications doubled during study period, but savings were achieved as other expenditures, mainly hospitalizations, and loss of productivity decreased by 50 to 75%. Treatment effectiveness increased as asthma related deaths, disability pensions, sick-leave payments and institutional care decreased significantly (50 to 70%). The cost-saving scenarios showed that a significant part (40%) of positive effects was attained by launch of new asthma drugs and asthma pipes from 1989 to 1994. The initiation of the national care programme with its focus on anti-inflammatory treatment from disease onset, improved diagnostics and more active self care further increased this positive trend. Conclusion: Comprehensive assessment of large patient cohorts and long term economical outcomes is a useful method for evaluation of outcomes in chronic diseases. Identification of different cost drivers is needed as the cost of new interventions is increasing and their benefits should ideally be assessed in relation to their broader societal influence.