ObjectiveWe examined the interaction of polymorphisms in the genes heme oxygenase-1 (HMOX1) and nitric oxide synthase (NOS3) in patients with preeclampsia (PE) as well as the responsiveness to methyldopa and to total antihypertensive therapy.MethodsThe genesHMOX1(rs2071746, A/T) andNOS3(rs1799983, G/T) were genotyped using TaqMan allele discrimination assays (Applied Biosystems, Foster City, CA, USA ), and the levels of enzyme heme oxygenase-1(HO-1) were measured using enzyme-linked immunosorbent assay (ELISA).ResultsWe found interactions between genotypes of theHMOX-1andNOS3genes and responsiveness to methyldopa and that PE genotyped as AT presents lower levels of protein HO-1 compared with AA.ConclusionWe found interactions between theHMOX-1andNOS3genes and responsiveness to methyldopa and that theHMOX1polymorphism affects the levels of enzyme HO-1 in responsiveness to methyldopa and to total antihypertensive therapy. These data suggest impact of the combination of these two polymorphisms on antihypertensive responsiveness in PE.