Abstract: A process for the isolation and recovery of .beta.-sitosterol substantially free of .alpha.-sitosterol from the unsaponifiables obtained from crude soap skimmings or from a crude sterol mixture containing .beta.-sitosterol, .alpha.-sitosterol and campesterol. The starting material is treated with an inorganic or organic acid in an organic solvent, whereby .alpha.-sitosterol reacts with the acid giving rearrangement products. The solution is cooled and filtered or the solvent is distilled off, whereafter the obtained crude .beta.-sitosterol is recrystallized from an organic solvent, to yield the pure material.