Given current knowledge of prescribing errors, standard paper prescription forms are inadequate for promoting high-quality outpatient prescriptions. A modified prescription form was designed and evaluated to reduce outpatient prescription errors. Eleven providers (nine physicians, two nurse practitioners) in an adult internal medicine clinic participated in a before-after trial of a modified paper prescription form. The modified form contained prompts for medication name, form, strength, dose, route, frequency, refills, quantity, indication, and additional directions. Writing the indication has face validity and has been recommended in the literature and has been useful in the practice. Providers used the modified prescription forms for one month. Prescriptions were reviewed using the records of the outpatient pharmacy located within the same building as the clinic. A total of 443 prescriptions were reviewed during the study period; 150 (34%) were completed using modified forms. Pharmacists documented problems with 2.3% of prescriptions (9/293 standard and 1/150 modified). Modified prescription forms significantly reduced clinically important prescribing problems compared to standard forms (p = .007). Based on the legal requirements of a prescription, modified forms decreased omission errors compared to standard forms (p = .01). Modified prescription forms reduced clinically important prescribing problems and prescription omission errors compared to standard forms.