We present the electroweak interactions as a gauge theory of the graded Lie group SU(2|1) in higher space-time dimensions. Besides giving the Weinberg angle θ W = 30° and mass of the Higgs bosons the number of leptons allowed in the model is related to the extra dimensions of space-time beyond four. A further prediction is that the mass of any lepton has the upper bound 2 −1 2 M W , where M W is the mass of the charged intermediate boson.