Background and Objectives: Without mandatory school-based education, Romania is a leading European country in teen pregnancy. This survey aimed at assessing the level of knowledge and the opinions about sexual education and sexual-related issues among mothers of female teenagers aged 13–18 years old. Material and Methods: The survey was conducted between 2015 and 2017 and had four parts, collecting data about sociodemographic variables, the level of knowledge about sexuality, sexually transmitted diseases, and contraception. The respondents were mothers of female teenagers hospitalized in a tertiary pediatric clinic. Data were analyzed using IBM Statistical Package for Social Sciences (SPSS) Statistics for Windows, version 25 (Inc., Chicago, IL, USA). Results: One hundred and thirty-five mothers (42.46 ± 6.81 years old) were included in the research. Most of them were from rural areas, had graduated secondary school, were Christian-orthodox, married, and with a stable job. More than half of the mothers (61.42%) declared that they personally knew adolescents that were already mothers. In great proportion, mothers proved good knowledge about sexual education, contraception, and STDs. They considered that the minimum age for becoming married, in general, is about M = 18.62 ± 2.09 years old but in the case of their daughters, mothers appreciated that the best age would be 23.56 ± 9.37. Mothers considered that they had good communication with their daughters (M = 4.28 ± 0.99) and two-thirds sustained that they had discussed with them about sexual activity, pregnancy, sexually transmitted diseases, and contraception. In case of unwanted pregnancy of their daughters, one-third of the mothers (38.50%) would advise their girls to continue the pregnancy and 7.40% mentioned the termination of pregnancy. Two-thirds of them (74.10%) agreed to school-based sexual education. In the order of preferred sources for sexual education, mothers mentioned parents (85.90%), teachers (33.30%), and family doctors (24.40%). Comparative results regarding their own sex life and that of their daughters are presented. Conclusions: School-based programs should meet parental beliefs about sexuality and sexual education. School, as a creator of values and models, should find the golden ratio to better shape the personal, familial, and social needs for the healthy sexual behavior of the new generation.