Rising costs of pharmaceuticals are a challenge to the public health care system. In collaboration with a company health insurance with 3143 members we analysed the economic benefit of reduced prescription fees for generic drugs in a 12-month period. Within the observation period 1 euro per prescription of a generic drug was reimbursed to the insurants. On the basis of 5 drug classes the prescribed proportion of generic drugs and the change in prescription pattern was computed. The acceptance of the intervention by the insurants was assessed using anonymous questionnaires. 42,219 drug prescriptons for insurants of the health insurance company were registered, with an overall cost of euro 843,954.95. In the observation period there was a 45% increase of the proportion of overall costs spent for generic drugs, from euro 78,325.65 to euro 110,419.90, together with a 38% increase of prescriptions of generic drugs. The expenditures for reimbursements of prescription payments amounted to euro 9,984 (euro 1-74 to insurants). In the 5 selected drug classes the proportion of generic drugs increased from 23% before the observation period to 40%, whereby a cost reduction of euro 2.47 per prescription was achieved. Taking into account an overall increase of prescriptions of the selected drugs, a cost reduction from euro 188,811.45 to euro 173,677.15 was accomplished. This intervention was considered useful by 84% of all insurants. Financial incentives for insurants by partial reimbursement of prescription charges are effective for increasing the proportion of generic substitutes and for controlling drug costs.