Mammalian cell cultures have been used for many decades in the manufacture of commercially significant products. These products, predominantly vaccines, have traditionally been produced in small laboratory vessels (i.e., roller bottles, T-flasks, etc.) without significant process monitoring or control. In the past fifteen years, with the advent of recombinant DNA technology, this situation has evolved somewhat albeit slowly. At the present time, several rDNA products based on cell culture technology are commercially available. However, the majority borrow process technology heavily from the past. As such, the focus until recently has been in areas such as robotic control of roller bottle based processes. For newer products in development, a greater level of change has occurred. For many such productions currently under clinical evaluation, the use of stirred fermentation vessels is more common. Typically these vessels are not equipped with highly sophisticated direct monitoring and control capabilities beyond that for temperature, agitation, head pressure, etc. There is, however, a trend toward advanced off-line monitoring of nutritional and metabolic parameters aimed at allowing better manual control of cell culture processes. In addition, the use of online biomass monitoring is coming into use. This paper summarizes the status and trends of industrial on-line and off-line analysis for mammalian cell cultures and describes the expected opportunities for the future.