Once viewed solely as fat storage cells, adipocytes and their adipokines have now been proven to be central for human health. Understanding that overweight and obesity may increase the risk for various diseases requires detailed characterization of adipokine function. Weight gain, weight regain, and fasting affect adipocyte health and accordingly their secretome. Different adipose tissue deposits exist and they vary in cellular composition and function. The evidence is strong of a role of adipokines in cancer, reproductive function, neurological diseases, cardiovascular diseases ,and rheumatoid arthritis. Adipokines are considered useful biomarkers for adipose tissue and metabolic health, and may be used as diagnostic tools in rheumatoid arthritis, cancer, or sepsis. This book contains 10 original articles and 9 review articles focusing on these bioactive peptides. Several articles deal with chemerin, an adipokine discovered more than 20 years ago. Data so far have resulted in promising insights related to its biological function. We are only beginning to understand the multiple roles of chemerin, the mechanisms regulating its activity, and the signaling pathways used by this chemokine. Adipokine receptor agonists and antagonists may result in the formulation of novel drugs and ultimately may lead to new therapeutic targets to be used in clinical practice.