Medication errors according to the National Coordinating Council Medication Error Reporting and Prevention (NCCMERP) are: as any preventable events that may cause or lead to inappropriate medication uses or harm to patients while the medications are in the control of health care professionals, patienst, or consumers. In the United States it was estimated 7,000 deaths every year caused by medication errors, and caused the budget for treatments due to medication errors to almost $ 2 Billion. This research aimed to determine types, frequencies, causes of errors in the pharmaceutical cares and the reporting systems. Data were collected using 4.9% patient names, 5.4% not giving information about the other effects of medicines prospectively for 3 (three) months with observation. Prescriptions were taken retrospectively 1 (one) month before the data collection. The research was conducted at 4 (four) big hospitals and 16 pharmacies in 4 (four) cities which had similarities in such errors as 86% prescribers who did not write patients' age, and 48.7% for weight. There were errors on 14.4% directions, 7.4% overdoses, 7.4% wrong dosages, and 1.8% drug interactions in the prescriptions. There were 14.9% no prescriber office addresses and 1.9% miscalculated the amount of medicines. In filling the prescription in pharmacies, 3.9% wrong amounts of divided powder were dispensed, 4.9% wrong names, 34% no precaution about side effects of the medicines. The prevention system is generally as follows: prescriptions are checked for the completeness; checked for patients' name, age, and weight; assessed patients' conditions if having any pregnancies, allergies, diseases and contraceptions. Doubted or unclear prescriptions were confirmed to the prescribers, refused to fill and returned to patients if the prescribers could not be reached. Each step of the process was checked double. If medication error occurs the pharmacist should contact the patient and correct the error. All medication errors were documented. Unfortunately there searchers had no access to these documents, either at the hospitals or the community pharmacies.