In order to measure the effects of clove oil on coral colonies, we used a clove oil-ethanol solution, a chemical used in particuler to anaesthetise and collect fishes in situ, and studied its effects on the hermatypic Scleractinaire, Pocillopora verrucosa. Loss of colouration and bleaching of coral colonies followed single or repeated exposures to variable doses of the anaesthetic solution. In experimental conditions, the solution had an impact on coral colonies, in particular after single exposure doses higher than 50 ‰.min. This value seems to constitute a threshold from which 100 % colonies are discoloured. A similar dose of solution was better tolerated by tested colonies when dispensed several times than when given at one go. In the natural environment, coral exposure to this type of anaesthetic product could therefore have a harmful effect on the colonies.