A simple procedure has been developed for the extraction of chlorophyll from intact portions of macroalgae prior to spectrophotometric analysis. The technique involves a short pretreatment (5 min) in a hyperosmotic solution of NaCl, or a suitable solute, of sufficient strength to cause plasmolysis followed by extraction (up to 6 h) in methanol or dimethylformamide. This procedure was fully effective in the extraction of chlorophyll from a range of green and brown marine macroalgae including Chaetomorpha capillaris (Kützing) Børgesen, Cladophora rupestris (Linnaeus) Kützing, Ascophyllum nodosum (Linnaeus) Le Jolis and Pelvetia canaliculata (Linnaeus) Decaisne et Thuret and the fresh water algae Cladophora sp. and Mougeotia sp. Alternative extractants, including acetone and dimethylsulphoxide were ineffective as extractants of chlorophyll from plasmolysed plant material. The technique is less time-consuming than conventional procedures based on grinding the tissue in a suitable solvent. Furthermore, the enhanced rate of chlorophyll extraction from plasmolysed plant material may decrease the risk of pigment degradation during sample preparation.