Algae have long been recognized as potential feedstock to produce oils. In recent years, the use of algae, in particular, Chlorella, for heterotrophic oil production has gained increasing interest due to its fast growth, ultrahigh cell density, and superior oil productivity. The current technology for heterotrophic production of algal oils, however, is still far from economically viable because of its high production cost. The opportunities that lie ahead for improving the production economics of heterotrophic algal oils will be the advances in exploration of low-cost carbon alternatives, advanced culture systems, and genetic engineering of algal strains for improvement as well as the biorefinery-based integrated production of oils and coproducts. Breakthroughs and innovations in these areas are sought to expand heterotrophic production of algae from high-value products to cheap commodity products of oils.