The present invention provides a method for monitoring adherence by a patient to a medication. The method comprises the steps of obtaining timing data in respect of each dose of a medication taken by a patient over a time interval, estimating the concentration of the medication in the patient's body over the time interval based on the dose timing data； determining the proportion of time over the time interval the concentration of the medication in the patient's body exceeds a target concentration； and calculating an adherence score for the patient based on the determined proportion of time the concentration of the medication in the patient's body exceeds the target concentration.
