ETHNOPHARMACOLOGICAL RELEVANCE: Leaf and seed decoctions of Casimiroa spp. are used in Mexican traditional medicine to treat high blood pressure. Previous researches showed as Casimiroa extracts are able to induce relaxation of rat aortic and caudal arteries. To study the influence of the aging, we determined the vascular effect induced by extracts of Casimiroa edulis and Casimiroa pubescens in arterial tissues from young and old rats. MATERIALS AND METHODS: The activity of Casimiroa edulis extracts: hexanic-leaf (Ce5), methanolic-leaf (Ce6), hexanic-seed (Ce7) and methanolic-seed (Ce8), and Casimiroa pubescens: hexanic-leaf (Cp9), methanolic-leaf (Cp10), hexanic-seed (Cp11) and methanolic-seed (Cp12) were investigated in precontracted caudal arteries of young (4 months) and old (20 months) rats. RESULTS: The Casimiroa extracts tested at 20 μg/ml induced vasorelaxation in phenylephrine-precontracted arterial tissues both in young and old arterial tissues. Methanolic seed extracts of Casimiroa edulis (Ce8) and Casimiroa pubescens (Cp12) caused a higher relaxation in young than in old arterial tissues. Nifedipine (0.01 μM) did not change the vasorelaxation induced by Casimiroa edulis extract either in young and old rat arterial tissues. CONCLUSIONS: The vasorelaxation induced by Casimiroa edulis and Casimiroa pubescens extracts is decreased from aging since the effects were higher in young than in old rat arterial tissues. However, the methanolic-seed extracts of both plant species induced a relevant vasorelaxation also in old arterial tissues. Thus the results support the traditional use of Casimiroa decoctions as antihypertensive, also in elderly.