This study was conducted to determine the effect of levels and timing of application of gibberellic acid (GA₃) on growth and yield components of common beans (Phaseolus vulgaris L.). Experiments were conducted at the Field Station Farm at the Faculty of Agriculture, University of Nairobi, Kenya during 1997 and 1998. "Mwezi moja" bean cultivar was used in study. Gibberellic acid (GA₃) was sprayed at 0, 2.5, 5.0 and 7.5 mg l^-1 to whole bean plants at 7, 14 or 28 days after emergence (DAE). The effect of GA₃ and timing of application on growth, yield and yield components was significant (P