A system and method for digital imaging and communications in security (DICOS) standard compliance validation. The system and method may validate both communication messages and files for compliance with the DICOS standard. In some embodiments, the system includes a processor for communicating with a test subject and a memory having program instructions stored thereon for performing a compliance test of the test subject to determine if the test subject is complaint with the DICOS standard. Execution of the instructions by the processor causes the processor to carry out the steps of: confirming that a transmitted DICOS message, e.g., a response or request, from the test subject is compliant with the DICOS standard; logging any errors in the transmitted DICOS message from the test subject in a validation report; and transmitting a simulated DICOS message, e.g., a response or request, to the test subject. In some embodiments, the steps further include, in response to the transmitted DICOS message, accessing a DICOMDIR file stored in the memory. The DICOMDIR file may be configured as a directory for DICOM file sets stored the memory. Transmitting the simulated DICOS message to the test subject may be performed in response to accessing the DICOMDIR file stored in the memory. Also, a DICOM file may be stored or retrieved from memory in response to accessing the DICOMDIR file stored in the memory.