BACKGROUND AND OBJECTIVES: Hypertension develops as a result of cardiac hypertrophy and fibrosis or as a result of exchange of the extracellular matrix. In particular, matrix metalloproteinase (MMP)-3 is a major enzyme involved in the reconstruction of the arterial intima through activation of other MMPs. We analyzed MMP-3 genotypes in hypertensive and normotensive adolescents and sought to determine if a particular genotype is a predictor of cardiovascular complications. SUBJECTS AND METHODS: Forty-four hypertensive adolescents and 59 healthy adolescents were included in this study. Serum aldosterone, renin, insulin, angiotensin converting enzyme (ACE), insulin, homocysteine, vitamin B12, folate, MMP-1, MMP-2, MMP-3, MMP-9, tissue inhibitors of matrix metalloproteinases (TIMP)-1, and TIMP-2 were measured. MMP-3 genotypes were analyzed using a polymerase chain reaction (PCR) primer. The carotid intima media thickness (IMT), diameter, and brachial ankle pulse wave velocity (baPWV) were evaluated using ultrasound. RESULTS: In hypertensive adolescents, blood pressure, anthropometric data, carotid IMT, baPWV, serum pro-MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were no different between the 6A/6A group and the 5A/6A group. Serum MMP-9 was higher in the 5A/6A group than in the control group. Aldosterone, insulin, and homocysteine were higher in the 6A/6A group than in the control group, and vitamin B12 and folate were lower in the 6A/6A group than in the control group. CONCLUSION: In conclusion, serum MMP-3 levels were not significantly different in different MMP-3 genotypes in hypertensive adolescents. However, few patients were included in this study. Further investigation is necessary to clarify the relationship between MMP-3 genotype and cardiovascular risk.