In order to reduce health care costs, the development of Follow-on Biologics (FoB) has received a lot of attention lately in the US. With the passage of the Patient Protection and Affordable Care Act in March of 2010, although the detailed scientific requirements still need to be sorted and clarified, a legal pathway exists in the US for the approval of FoB. Statistically-related issues and challenges associated with the development of FoB will be discussed. These include the establishment of biosimilarity of the critical quality attributes, pharmacokinetic biocomparability, and clinical/pharmacodynamic comparability including the selection of endpoints, designs, and the setting of margins. Particular attention will be paid to the topic of margins in clinical trials where scale as well as fixed margin versus synthesis methods will be discussed.