A simple and rapid spectrophotometric method for measuring recombinant inclusion body concentrations in the presence of Escherichia coli cell debris has been applied to monitoring the performance of an industrial disc stack centrifuge. Turbidimetric measurements were made at two wavelengths, i.e., 600 nm and 420 nm, and the ratios of OD600nm/OD420nm related to the particle composition in suspension. The principle behind the technique is that inclusion body particles scatter light at 600 nm more effectively than do smaller cell debris particles when compared with the degree of light scatter at 420 nm. This technique may have broad potential application in developing an automatic monitoring and control system for industrial-scale inclusion body recovery.