Traditionally Western Herbal Medicine (WHM) uses ‘whole plant extracts’, typically presented as liquids, teas and powders, with no formal measurement of identified plant constituents. In contrast, ‘standardised extract’ preparations offer a guaranteed minimum content of specified constituents, as identified in modern research. A limited number of these preparations, referred to here as ‘highly standardised extracts’ and largely presented as tablets, offer a much higher dose of ‘active constituent/s′ than is present in the whole plant extract. They are the focus of this study. The study investigated how herbalists have come to use highly standardised extracts and their attitudes towards them, with a view to informing the debate and the wider interested community.