A process for sepn. of protoescigenin (I) monohydrate from horse chestnuts (Aesculus hippocastanum L) beta-escin by alk. or acidic hydrolyze extn. with ternary MeOCMe3/H2O/MeOH mixt., then pptn. with H2O and following purifn. by recrystn. from binary iso-PrOH/cyclohexane mixt. was developed and implemented under pilot plant conditions. The I yields were 197-209 g/2.00 kg under lab. and 210-218 g/3.00 kg under pilot-plant conditions. The final product contained 1.0-2.5% of barringtogenol (II) impurity. [GRAPHICS]