A method, system and computer program product for facilitating inter-proxy communication via an existing protocol. A proxy receives a message (e.g., request message) using a protocol, such as HTTP. If the proxy determines to add proxy relevant information to the message, then the proxy defines a new message header for the inter-proxy communication, which is added to the existing header section of the message. The proxy relevant information is then added in the newly added message header of the message. The message with the proxy relevant information is then transmitted to a subsequent proxy using the protocol of the underlying request-response transaction. In this manner, inter-proxy communications are enabled via an existing protocol (e.g., HTTP) that is used in the request-response transaction so that proxies can communicate with one another pertaining to matters (e.g., maintenance schedule) unrelated to the original intent of the transaction using the existing protocol (e.g., HTTP).