A new, simplified open-vessel microwave extraction (OVME) method has been used to prepare aqueous extracts of Sennae folium and Tiliae flos . For comparison, extracts were also prepared by classic pharmacopeial methods — decoctum, infusion, and ultrasound extraction. The extracts prepared by the different extraction methods were compared by over-pressured layer chromatography (OPLC), followed by video and UV-densitometric evaluation. We demonstrated the applicability of rapid OPLC separation combined with UV densitometry for comparison of extracts prepared by different methods. OPLC-UV is suitable for rapid, non-destructive investigation of multicomponent preparations of biological origin.