This book constitutes a key reference on the use of algae in the biopharmaceuticals production field; providing an updated outlook on the achievements accomplished thus far and transmitting a prospective view for this biotechnological application. This book provides a detailed description of the technology as well as an updated outlook of the strides achieved thus far in the field of algae-based biopharmaceuticals. Algae constitute attractive expression hosts for the production of recombinant proteins with medical applications. Among the features that make them attractive candidates are: low cost, fast growth, wide biosynthetic capacity, and absence of human pathogens; which constitute substantial advantages with respect to bacterial and mammalian systems. First, the features of algae as convenient hosts for the production of BFs are analyzed in terms of production costs, biosynthetic capacity, and safety (Chapter 1). Second, the genetic engineering tools for algae-species are described. Nuclear and chloroplast-based expression approaches are analyzed and compared in terms of biosynthetic advantages, gene expression complexity, and DNA transfer approaches (Chapter 2). In the following sections, chapters 3 to 7, the state of the art on producing distinct types of BFs in algae species is presented. Although this book is mainly focused on BFs, considering that the production of compounds with health-promoting properties are achieved using genetically-engineered algae strains, chapter 8 deals with nutraceuticals. In the ninth chapter, the developments reported thus far are placed in perspective and challenges for the field are discussed. Critical future prospects comprise the following: optimizing large-scale production in bioreactors, implementing glycoengineering approaches, optimizing nuclear expression, exploring new approaches for oral delivery, and implementing regulatory frameworks to accomplish technology transferand regulatory approval of algae-made BFs.