Willbros' Outstanding Convertibles Senior Notes Become Convertable

Pursuant to Section 12.1(a)(i) of the Indenture governing Willbros' outstanding 2.75% Convertible Senior Notes due 2024 (the "2.75% Notes"), the 2.75% Notes become convertible today, August 15, 2007, at the option of the holders of the 2.75% Notes, and the 2.75% Notes will continue to be convertible through November 14, 2007.