With the increasing burden of cancer, there is a growing need for efficient diagnostic, prognostic and prediction tools to facilitate patient management. The knowledge of immune system and malignancy interplays, gave rise to a whole new paradigm of molecular investigation, using immune-related markers and/or immune-based approaches. This chapter aims to provide an introductory review of immunodiagnostic and immunoprognostic methods in cancer management. Routinely used and emerging fields of diagnosis and prediction are classified based on sample type and molecular category. Solid tissue sample immunodiagnostics roots in immunohistochemistry and further evolves into in situ sequencing of nucleic acid, multiplexing of various cellular markers and mutation profile analysis. The revolutionary discovery of liquid biopsy-based markers brought the advantage of minimally invasive whole-body analysis of malignancy, as well as dynamic monitoring of disease. Circulating tumor markers encompass a wide spectrum of molecules from mutation products and overexpressed nucleic acids to antitumor autoantibodies formed by the immune system and exosomes carrying all these molecular subtypes. The utility and relevance of each target mainly depends on tumor type and the aim of interpretation. Molecular cancer research relies on the effects of malignancy on genome, proteome, and immunome. Immunodiagnostic technologies aim to investigate these alterations either using immune-related markers or immune-related methods.