[en] Electroweak radiative one-loop corrections to Higgs boson pair production in t bar t fusion processes are calculated in the two-Higgs-doublet extension of the standard model. The numerical size of the nonstandard corrections is discussed for the process t bar t→H₀H₀. The relative difference between the predictions of the two-Higgs-doublet model and the minimal standard model for a light scalar M_H1 and heavy M_H2 and M_Φ easily exceeds -10% in the forward and backward directions. In particular the angular-dependence corrections owing to the nonstandard Higgs bosons get larger where the box and cubic Higgs boson vertex corrections constitute the dominant part of the radiative corrections. copyright 1996 The American Physical Society