The human dipeptidyl peptidase IV (hDPPIV/CD26) is expressed as an immune response in some cancer cells as well as intestine and incretin metabolism, and deficiency of the enzyme leads to metabolic disorders. In the present study, recombinant hDPPIV/CD26 genes were expressed in baculovirus-insect cell systems in a 5-L stirred-tank fermenter. Because of the shear sensitivity of the insect cell line, production from insect cells should be performed in new-generation type bioreactors, which are commonly more expensive than microbial fermenters. To optimize the process, hydrodynamic parameters and oxygen consumption of Sf9 cells at 1.5 L and 3 L were monitored, and a certain amount of serum was added to the production medium to decrease shear and stabilize the growth of insect cells that normally do not need serum addition. In this study, dimensionless numbers and some hydrodynamic parameters were calculated in 1.5 L, and predictions were made for 3 L fermenter volumes. Agitation rates of 60 rpm were determined to protect insect cells against damaging shear stress. Regarding the agitation rate, oxygen mass transfer coefficient (kLa) was 0.0129 min-1 for 1.5 L and was kept constant for 3 L (0.0133 min-1). The maximum enzyme activity from microbial fermenters was 2.37-fold higher than activity from T-flask in our previous work. The infection efficiency of transfected cells was 78%-81% in the 1.5-L and 3-L fermenters.