Varietal differences in susceptibility (as assessed by the proportion of affected plants) to wilt of cotton caused by Verticillium dahliae Kleb., were observed in south-eastern Queensland. The progression of the disease within individual plants, however, was similar in all varieties. Deltapine Smoothleaf, the most widely grown variety in Queensland was one of the most susceptible varieties. Derivatives of Rex or Dixie King were less affected. The disease caused a difference in yield between healthy and diseased plants which could be as high as 30 per cent.