e18014 Background: With the increasing use of oral anticancer treatments understanding adherence patterns and patient’s information about therapy has become critical. Enzalutamide (ENZ) and Abiraterone acetate (AA) are orally administered drugs approved for the treatment of mCRPC widely prescribed; however, scarce information is available about treatment compliance and patient’s information about these compounds. This study aims to evaluate the adherence to AA and ENZ and the patient’s drug knowledge in mCRPC patients. Methods: A 20-question survey is being delivered to patients with mCRPC receiving either AA or ENZ in 8 centers across Spain. Questions cover items such as demographics, drug information, adherence and perceived benefits among other topics. Surveying is still ongoing. Results: Fifty patients have completed the survey at this time. Mean age is 72 years (range 58-87), educational level is basic in 56 %. Median duration of treatment was 9,5 months. Adherence reported is very high with 84% of the patients taking 100% of prescribed doses and 100% more than 75%. Treatment compliance does not seem to decrease over time despite only 42% of the patients reported the use of devices to secure adherence. A high compliance correlated with better symptom control. Nonetheless, many areas of improvement have been also identified. About a quarter of the patients (26%) ignored the name of the drug they were receiving and 24% whether or not they were in a clinical trial. Almost all patients were not aware of the planned duration of treatment and 70 % recognized that they did not know the consequences of a bad adherence. Eleven patients (22%) were taking AA with food outside of a clinical trial and three patients (6%) reported inadequate dosage (i.e q 12h). Conclusions: While in other diseases adherence to oral therapies has been identified as a potential limiting factor with impact in efficacy, in our series of mCRPC treatment compliance was high and maintained overtime. Yet, serious patient education pitfalls were identified. Data collection is ongoing and further analysis will be presented.