To efficiently produce a high quality extract of guava leaves by subjecting guava leaves to extraction with water or a hydrophilic solvent, partially concentrating the extracted liq., removing a material slightly soluble in the extracting solvent and concentrating the partially concd. liq. again.

Guava leaves are subjected to extraction with water, a hydrophilic solvent or a mixture of them. The hydrophilic solvent is preferably prim. alcohol or lower ketone and is especially preferably methanol, ethanol, butanol or acetone. The extraction is preferably carried out with a mixed solvent consisting of water and such a hydrophilic solvent. The resultant extracted liq. is partially concd. under reduced pressure until the volume is reduced to 1-10%, preferably about 50-60% of the original volume at room temp. to 70°C, preferably about 30-40°C. A material slightly soluble in the extracting solvent is removed from the concd. liq. by sedimentation or extraction and the treated partially cond. liq. is properly concd. optionally under reduced pressure.