Microfluidic chip devices and their application to sensitive chemical and biological analyses have attracted significant attention over the past decade. The miniaturization of reaction systems offers practical advantages over conventional benchtop systems. In this case, however, a highly sensitive on-chip detection method is important for the monitoring of chemical reactions as well as for the detection of analytes inside the channel because the detection volume in a micrometer-size channel is extremely small. Recently, a surface-enhanced Raman scattering (SERS) technique is being regarded as a potential candidate for the highly sensitive detection of analytes in a microfluidic chip. This review provides a general survey and an in-depth look at recent developments in SERS techniques for the biological/environmental analysis of minute analytes in a microfluidic chip.