This study analyzes relationships between the number of drug-related problems detected in community pharmacy practice and the educational level and other characteristics of pharmacy personnel and their work sites. Random samples of pharmacists, prescriptionists and pharmacy technicians were drawn nationwide in Sweden. One hundred and forty-four (63%) of those meeting the inclusion criteria agreed to take part. The participants documented medication-related problems, interventions and patient variables on a data collection form. The drug-related problems were weighted by the number of patients served by each professional. The regression analysis showed the educational level of the professional to have a statistically significant effect on the detection rate, with pharmacists finding on average 2.5 more drug-related problems per 100 patients than prescriptionists and about 3.6 more than technicians. Previous participation in a study or activity on drug-related problems and the size of the pharmacy also had statistically significant effects on the problem detection rate. The use of open-ended questions to create a dialogue with the patient seemed to be a successful means to discover problems. The results of this study indicate the importance of education and training of pharmacy personnel in detection of drug-related problems. This findings speaks in favor of increasing the pharmacist to other personnel ratio, provided the higher costs will be offset by societal benefits.