The objectives of this study were (1) to determine the dimensions of pharmacists' effort (work) and (2) to measure the effort and its dimensions required when processing prescriptions with various characteristics, new/refill, presence and category of drug-related problems (DRP), drug class, patient age, and payment method. Interviews were conducted with community pharmacists to determine the dimensions of their effort when processing prescriptions. Time, cognition and communication were considered as the most important dimensions. A questionnaire containing five prescriptions with varying characteristics was mailed to 1,524 community pharmacists in the state of Maryland. On a visual analogue scale with equal intervals, respondents were asked to evaluate time, cognition, communication and overall effort required to process each prescription. Analyses were performed using factorial ANOVA with repeated measures of R{dollar}\sb{lcub}\rm x{rcub}{dollar} (new/refill-presence and category of DRP). Pharmacists' perception of time, cognition, communication, and overall effort was approximately double when prescriptions contained a DRP such as a drug interaction, or excessive dosage and was increased by approximately 50% when a prescription was processed for a non-compliant patient. Age of the patient or payment method did not influence the overall effort (nor its dimensions) involved in processing prescriptions. Drug class had an effect on overall effort (and its dimensions) and an interactive effect with R{dollar}\sb{lcub}\rm x{rcub}{dollar} on overall effort and communication scores. The results have implications for reviewing compensation of pharmacists in the provision of pharmaceutical services which can be associated with the prevention and resolution of drug-related problems. A typology of three types of pharmaceutical services has been derived from the study: (UNFORMATTED TABLE OR EQUATION FOLLOWS){dollar}{dollar}\vbox{lcub}\halign{lcub}#\hfil&&\quad#\hfil\cr &{lcub}Relative\ value{rcub}&\cr &\ \ \underline{lcub}of\ effort{rcub}&\underline{lcub}Prescription\ characteristics{rcub}\cr\cr &1.0&Prescriptions (new or refill) without\cr&&a drug-related problem;\cr &1.5&Prescriptions for non-compliant patients;\cr &2.0&Prescriptions with a drug-related problem that\cr&&require an intervention with the physician.\cr{rcub}{rcub}{dollar}{dollar}(TABLE/EQUATION ENDS) Concerning the dimensions of effort, approximately half of the variance of overall effort was explained by communication and cognition. Pharmacists did not relate overall effort to time per se.