There is increasing interest in adding value to textiles by the use of natural products. Many of the plants from which natural dyes are obtained are, for example, also known to have medicinal properties. In the current study, the antimicrobial properties of eleven natural dyes against three types of Gram‐negative bacteria were studied experimentally. Seven of the dyes showed activity against one or more of the bacteria. The minimum inhibitory concentration for three selected dyes was determined. The results demonstrate that certain dyes are able to reduce microbial growth almost completely in the case of Escherichia coli and Proteus vulgaris. Selected dyes would therefore be valuable for the dyeing of sheets and gowns for hospital use, and on articles which are less suitable for laundering such as mattresses and upholstery. The dyes examined exhibited good wash fastness and the antibacterial effect is therefore likely to be durable.