Cloud service monitoring is a critical need for both providers and customers to assess the state of resources and the level of delivery of services. However, existing Cloud service monitoring methods are typically inapplicable in case the targeted service parameters are inaccessible, e.g., Cloud Service Providers do not allow external access to some service parameters for varied reasons (proprietary IPR, privacy issues, security concerns or simply access difficulties). Hence, alternate Cloud service monitoring approaches are needed to address this issue. Nonetheless, Cloud services are not provided in isolation and very often share common resources with other services that naturally introduces service dependencies between different services. In this paper, we propose a novel Cloud service monitoring approach which targets such dependencies to conduct indirect monitoring of inaccessible Cloud service parameters by using monitoring information collected from other Cloud services. The proposed monitoring approach can also assess the reliability of the monitored result. The presented case study validates the applicability of the proposed indirect monitoring approach. © 2017 IEEE.