The low probability of a drug candidate's clinical success, the time consumed and the high cost of bringing a drug from concept to market emphasizes the need for new approaches to drug discovery. Recent innovations in microfluidic technologies, including organ-on-a-chip, droplet microfluidics and high-throughput screening are revealing the potential of these platforms to address some of these challenges, due to the small volume of samples consumed, short processing time, and improved process control. Here, we review selected recent progress in the development and application of microfluidic technologies in drug screening and drug delivery, highlighting the trends and associated challenges.