Cancer associated fibroblasts (CAFs) comprise a heterogeneous population that resides within the tumor microenvironment. They actively participate in tumor growth and metastasis by production of cytokines and chemokines, and the release of pro-inflammatory and pro-angiogenic factors, creating a more supportive microenvironment. The aim of the current review is to summarize the origin and characteristics of CAFs, and to describe the role of CAFs in tumor progression and metastasis. Furthermore, we focus on the presence of CAFs in hypoxic conditions in relation to multiple myeloma disease.