Protein-based drugs constitute about a quarter of new approvals with a majority being glycoproteins. Increasing use of glycoproteins, such as monoclonal antibodies, at high therapeutic doses is challenging current production capacity. Mammalian cell culture, which is currently the production system of choice for glycoproteins, has several disadvantages including high cost of goods, long cycle times and, importantly, limited control over glycosylation. In view of this, several expression systems are currently being explored as alternatives to mammalian cell culture, these include yeast, plant and insect expression systems. Each of these has different merits for the production of therapeutic glycoproteins and can lead to enhanced therapeutic efficiency.