To describe the processes of care used by community pharmacists participating in the Pharmaceutical Care Research and Education Project (PREP) in terms of drug-related problems (DRPs), pharmacists' recommendations, and status of DRPs at follow-up, and to determine characteristics associated with DRPs. Descriptive analysis of the treatment group from a larger randomized, controlled cluster design. Five independent community pharmacies in Alberta. One hundred fifty-nine patients who were covered under Alberta Health and Wellness's senior drug benefit plan (i.e., 65 years or older), were taking three or more medications concurrently according to pharmacy records, were able to complete telephone interviews as determined by pharmacists, maintained residence in Alberta for 12 of the 15 study months, agreed to receive their prescription medications only from the study pharmacy during the study period, and provided informed consent. Frequency of DRPs, recommendations, status of DRPs, and analysis of clinical results as determined during pharmacists' follow-up care. In telephone surveys, patients reported taking 4.7 prescription medications per day, but pharmacists documented 8.7 prescription medications per day in their records. Pharmacists documented 559 DRPs, a mean (+/- SD) of 3.9+/-3.2 problems per patient. Approximately 39% of problems were actual DRPs, while 60% were potential DRPs. Medical conditions associated most frequently with a DRP involved the respiratory, cardiovascular, and musculoskeletal systems. The most common DRP categories were "patient requires drug therapy" or "patient requires influenza or pneumococcal vaccination." Pharmacists wrote 551 initial clinical notes using the subjective, objective, assessment, plan (SOAP) format, and they recorded 346 follow-up interventions, also using SOAP notes. Counseling, preventive consultations, and clinical monitoring represented 40% of their recommendations. In 80% of situations, the pharmacist made the recommendation directly to the patient. On follow-up, 40% of the 559 DRPs identified were resolved, controlled, or improved. Patients accepted 76% of pharmacists' recommendations, and physicians accepted 72% of pharmacists' suggested resolutions of DRPs. Pharmacists were more likely to follow up about actual DRPs, as compared with potential ones; overall, they followed up on 62% of identified DRPs. Pharmacists identified more DRPs for study patients than previous community-based, observational studies have reported. Undertreatment appears to be a prevalent DRP. Community pharmacists' recommendations to prevent and resolve DRPs were made primarily to patients and were well accepted. More follow-up was needed for all DRPs. When follow-up occurred, the DRP results generally showed improvement.