Habitual prospective memory (HPM) may be important in medication adherence. The present study utilized a computer-based task of HPM to (1) examine the relationship between HPM performance and medication adherence and (2) explore whether, and under what conditions, HPM could be enhanced. Forty-eight elderly diabetic patients were randomly allocated to one of four HPM task conditions: no cue, visual cue, auditory cue or dual cue (auditory and visual cue) to aid performance. Medication adherence was monitored for at least 10 days using electronic dose event monitors. HPM task performance was optimal in the dual cue condition and there was some evidence of a relationship between HPM task performance and indices of medication adherence.