Studies were conducted on the production of phosphodiesterases by Nicotiana tabacum 1507 cell suspension in an aqueous two-phase system formed by adding 4% polyethylene glycol (mol wt 20,000) and 7.5% dextran (mol wt 70,000) to the medium. The time course of growth, biosynthesis, secretion, and partitioning of phosphodiesterases was followed in comparison with N. tabacum 1507 cultivation as a free suspension. Partitioning of phosphodiesterases took place mainly in the bottom dextran phase, and a possibility was revealed for obtaining an enzyme preparation with high phosphodiesterase activity.