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In classical Dravyaguna, rasa (taste) is the first and most accessible property of a drug. It is held to reflect the drug’s elemental composition (panchamahabhuta) and to predict its actions on the dosha and tissues. Modern research has begun to test whether rasa categories correspond to measurable chemistry and to recorded pharmacological activity. This review appraises three lines of evidence. First, in a database of 183 Ayurvedic plants, predominant taste was significantly associated with ethnopharmacological actions, with 109 significant taste–action associations, only four of which contradicted traditional sources. A companion database links 431 Ayurvedic plants to 438 identified tastant molecules. An independent analysis of 700 drugs from Dioscorides’ De Materia Medica, rated by a trained sensory panel, found that taste qualities predicted therapeutic uses, with bitterness associated with therapeutic versatility. Second, electronic-tongue and spectroscopic studies distinguished sweet from bitter plants well, sweet plants resembling sucrose. Separation of pungent, sour and astringent groups was less clear, and bitter plants did not match caffeine or quinine standards. Thin-layer chromatography has localised astringent-tasting, tannin-containing fractions. Third, the discovery of taste receptors outside the mouth, in the gut, airways, heart and elsewhere, offers a plausible mechanism by which taste-active compounds could have systemic effects. Taken together, the evidence supports rasa as a meaningful, if coarse, descriptor of chemistry and action. It also shows that classical rasa assignments need reproducible sensory methods. We propose a research agenda combining trained sensory panels, chemical profiling and receptor pharmacology.