Age Marriage Maturation (PUP) is part of the National Planning Family program to increase the age of first marriage minimum 21 years old for women and 25 years old for men. Age Marriage Maturation Program (PUP) will have an impact on increasing the first age marriage, which it will turn lower the Total Fertility Rate (TFR). The purpose of research is to explore the knowledge of adolescents about the Age Marriage Maturation program (PUP) in SMKN 3 of Blitar. This research use descriptive design with 571 populations from SMKN 3 Blitar's students and the sample is 235 students with proportional random sampling technique. The collection data by questionnaires. The results is 83% good knowledge, 15,3% sufficient knowledge, and 1,7% less knowledge. Knowledge of adolescents has been good, but needs to be improved in relating matters about influence of the health aspects to the Age Marriage Maturation (PUP). Suggestions for school is should be information about Age Marriage Maturation (PUP) presented attractively by picturial media.