Background: Pharmaceutical pictograms have been designed to help communicate medication instructions to patients. Pictograms used within a patient counseling service can significantly improve medication compliance and adherence. The study aimed to assess the improvement of adherence to therapy with the use of pictogram intervention in comparison to standard pharmacy practice in community pharmacies. Methods: Pictograms informing about the proper way of using metoprolol prolonged release tablets were designed to be used on the packages of the drug in community pharmacies. Pharmacies belonging to a pharmacy practice-based research network were randomly assigned to a group using pictograms when dispensing the drug or one following their normal practice. At the first visit, all patients answered a structured questionnaire about their medication behavior in the preceding 7 days. The same questions were asked 4 weeks later to follow-up treatment adherence change and compare studied groups. Descriptive statistics was used to analyze the data, and the McNemar test was used to compare categorical data at baseline and follow-up. Results: Of a total of 253 patients screened, 117 and 104 patients completed the study in the standard practice and pictogram groups, respectively. The use of pictograms significantly improved medication adherence in the following areas: not omitting doses (p < 0.0001), not crushing tablets (p = 0.004), number of tablets/day (p = 0.49), and time of use (p = 0.001), compared to the standard practice group. Conclusions: Our results suggest that pictograms are effective in conveying messages about the proper way of using medications, and they increase treatment adherence, in comparison to standard dispensing practice.