Background: Mental illness in the world and in Indonesia shows a high prevalence rate. The concoction recipe is a prescription pattern that is widely used in psychiatrist polyclinic. Prescription concoctions in psychiatrist polyclinic can lead to medication errors. The incidence of drug errors in psychiatrist polyclinic can cause therapy failure in patients. Methods: This research is a descriptive observational study with a cross-sectional design. Collecting data in this study prospectively with purposive sampling method. The sample used was an outpatient prescription for the mental health polyclinic at the Kardinah Regional General Hospital (RSUD) Tegal City which complied with the inclusion and exclusion criteria of 145 concoction recipes. Results: The percentage of medication errors in the prescribing phase was 11.91% without a doctor's SIP, 7.07% did not have drug dosage units (mg, gram, mL, L), 5.75% did not have a dosage strength, there was no patient weight of 0.41%, there was no patient address of 0.16%, there were no initials of the prescriber of 11.91% and there were drug interactions of 3.37%. The percentage of medication errors in the dispensing phase was 0% in all aspects while in the administration phase, 11.83% did not explain drug indications, 11.91% did not explain contraindications, 11.83% did not explain side effects, did not explain Beyond Use Date as much as 11.91%, and does not explain drug storage as much as 11.91%. Conclusion: The percentage of medication errors in the three phases as a whole, namely the prescribing phase was 40.59%, the dispensing phase was 0% and the administration phase was 59.41%.