OBJECTIVES: To study medication compliance patterns regarding dosing, timing and adherence under real life conditions. Using a new electronic blister pack system. METHODS: A total of 37 volunteers from three study centers were each furnished with an electronic blister holder (“monitor”) and three blister packs containing 14 placebo capsules each (trial duration: six-weeks). The monitor measured the disruption of conductive lines printed on aluminum carrier foil under each capsule and stored this information (date and time) for evaluation at the end of the study. Patients had to take out one capsule daily in the morning over the entire study period. Also patients received a CRF and a radio-controlled clock such that date and time of the event could be manually recorded by the patient as well. Data were considered accurate if the information stored in the monitor and the corresponding CRF entries were within a time window of ± 15 min. RESULTS: All recordings of the electronically stored information matched the data documented on the CRFs. This indicates the accurate documentation of the volunteers, as well as the correct functioning of the monitors. Evaluation of the data, however, showed a wide intra- as well as interindividual variation in the time patterns of the volunteers. Three clusters of time preference were detected – mornings, noon and late night. Further, periods of non-compliance („drug holidays”) as well as lack of adherence (discontinuation of medication before the end of the study period of six-weeks) could be documented. CONCLUSIONS: The use of the new electronic blister system improves compliance measurement under real life conditions. Combining compliance information with other outcome parameters will help in better quantifying and optimizing the impact of patient compliance on clinical and economic outcomes under real life conditions.