Pharmacotherapy is the most frequently used treatment modality among the older adult population. Consequently, medication adherence represents an important treatment consideration. The present study was conducted to assess the extent of medication adherence in the New Zealand sample, and evaluate the effectiveness of an external cognitive support in a sample of 50 community-dwelling older adults (M = 70.70, Mdn = 72.00, SD = 8.12). A randomised controlled trial to compare the usual medication practice with a medication calendar was conducted. The present sample had high levels of medication adherence, with high adherence measured on an adherence ratio 97% (range 82% to 109%), and low rate of medication errors (19 errors). There were no significant differences in medication adherence between intervention and control groups (ps >.05). However, consistent with prior research, there was some evidence to suggest that female participants were less compliant and made more errors than male participants. Further research on larger more representative older adult samples is warranted.