We study the new features of N = 1 supergravity coupled to the gauge interactions SU(2) L × U(1) Y × SU(3) c of the standard model in the presence of heavy families. We assume the minimal set of Higgs fields (two SU(2) L doublets H 1,2), the desert between M W = 100 GeV and M G = 2 · 10 16GeV and perturbative values of the dimensionless parameters throughout this region. Using the numerical as well as the approximate analytic solution of the renormalization group equations, we study the evolution of all the parameters of the theory in the case of large (≳ 0.5) Yukawa couplings for the fourth family. Yukawa couplings and certain mass parameters of the theory exhibit an interesting infrared behavior. We also investigate the implications of heavy families on the low-energy structure of the theory. The desired spontaneous symmetry breaking of the electroweak symmetry with M W = 100 GeV takes place only for a rather unnatural choice of the initial values of certain mass parameters at M G. Two scenarios are possible, depending on the value of m 3 2 . For m 3 2 ⩽ 200 GeV the vacuum expectation pattern 〈 H 1〉 ≈ 〈 H 2〉 ≈ 123 GeV emerges necessarily in an interplay of the tree-level Higgs potential and its quantum corrections. The quark masses of the fourth family are m ̃ U ≈ m ̃ D ≈ 135 GeV , while the mass of the fourth charged lepton has an upper bound m ̃ E ⩽ 90 GeV . Further characteristic features of this scenario are one light neutral Higgs field of mass m H 0 ≲ 50 GeV and gluino masses m λ 3 ≲ 75 GeV. For m 3 2 ⩾ 200 GeV one obtains a scaled-up version of the three-family, heavy top scenario with 40 GeV ≲ m ̃ U, D ≲ 205 GeV and all superparticles heavier than 150 GeV except the photino, gluino, one chargino and one neutralino.