Protein-based therapeutics have enjoyed great success over thepast decade. Unfortunately, this clinical success has come with aheavy price tag that is due to the inherently high costs of thecapitalization and production of these complex molecules usingcurrent mammalian-based fermentation systems. Recentprogress has been made in the production of recombinantproteins, including antibodies, in the eukaryotic unicellular greenalgaChlamydomonas reinhardtii.C. reinhardtiioffers anattractive alternative to traditional mammalian-based expressionsystems for several reasons, including its ability to provide stableplastid and nuclear transformants rapidly and its inherently lowcosts for capitalization and production.