The potential preventive effects of nicardipine (100 mg/kg q.d., orally, for 6 weeks, starting at the 6th week of age) on genetic hypertension development (GHD) have been investigated in young SHRs. Furthermore, at the end of the treatment period, segments of mesenteric arteries were isolated in order to determine their vascular compliance and reactivity to noradrenaline and the total proteins content and the amount of DNA in the vascular wall. At the end of the treatment period and 20 hours after the last drug administration, nicardipine exhibited no preventive effects against GHD but heart rate was lower in treated than in control animals. Mesenteric vascular compliance was not treatment-affected but the maximal contractile response of the vessels to noradrenaline was slightly decreased. Finally, total proteins and DNA contents of the vascular wall were unchanged. It thus appears that there is a striking parallelism between nicardipine's lack of effects on resistance vessels' compliance and vascular total proteins and DNA contents on the one hand and the drug's inability to oppose GHD in young SHRs on the other.