The intensity of the hydrodynamic stress on cell aggregates is closely related to the growth and production of secondary metabolites. In this study, we have investigated the effects of cell aggregation in suspension cultures of Psoralea corylifolia on growth and phytoestrogens production. HPLC analysis revealed that cell aggregates of 1.2 mm size produced maximum amount of daidzein (2.84% dry wt.) and genistein (0.47% dry wt.) on day 20. The phytoestrogens production level was ~2-fold more than that of heterogeneous cell aggregates (control) in suspension cultures and 11-fold more than field grown plants. Analysis of spent medium revealed no leaching of phytoestrogens. Results indicated that certain degree of cell aggregation in suspension cultures directly supported phytoestrogen production.