Colour is one of the most important quality parameters of table grapes. Ethephon can be applied to improve the colour of table grapes. Trials were conducted in Western Australia to investigate the effect of ethephon on low berry colour and other quality parameters of two new clones (306 and 314) of Crimson Seedless table grapes developed in Western Australia. The ethephon effect was studied in comparison with clone 5560, which was the standard clone imported from California. The grape clones were established at two locations in Western Australia having different types of soil and environmental conditions. Ethephon was applied (300 ppm Ethrel®) to improve the colour development. Physical measurements demonstrated that clones 306 and 314 were better than the imported standard clone in terms of berry weight, length and width. Sensory evaluation by 70 panellists revealed that clone 314 with ethephon application received significantly higher sensory scores for sweetness, crispness, flavour and overall acceptability compared with the standard clone. The acidity level was higher in clone 314 than the standard clone at the same °Brix level and had a positive effect on flavour and overall acceptability. Ethephon treatment reduced the berry crispness in the standard clone and clone 306 but had no effect on the crispness of clone 314.