ABSTRAKLatar belakang : Remaja dalam memasuki masa kanak-kanak menuju masadewasa tanpa pengetahuan yang memadai tentang seksual. Sikap seks bebasremaja bisa berwujud positif ataupun negatif. Hasil survey BKKBN di Indonesiatahun 2013, anak usia 10-14 tahun yang telah melakukan kegiatan dalam upayamemenuhi dorongan seksual mencapai 4,38%, sedang umur 14-19 sebanyak41,8%.Tujuan : Mengetahui hubungan tingkat pengetahuan tentang seks bebas terhadapsikap seks bebas remaja SMK Negeri 1 Sukoharjo.Metode : Observasional analitik dengan pendekatan cross sectional, jumlahsampel 185 orang yang dipilih secara probability sampling dengan jenisproportional sampel. Data tingkat pengetahuan dan sikap seks bebas diperolehdari mengisi kuesioner. Kedua data diolah menggunakan chi square.Hasil : Sebanyak 77,30 % remaja berpengetahuan baik tentang seks bebas danpengetahuan cukup 22,70 %. Dimana sikap negatif remaja 68,10 % dan sikappositif remaja terhadap seks bebas 31,90 %. Hasil uji chi square pada penelitianini menunjukkan adanya hubungan antara kedua variabel dengan nilai signifikansi(P) sebesar 0,000 (P < 0,05).Kesimpulan : Pengetahuan baik dapat menunjukkan sikap negatif maupun sikappositif.Kata Kunci : Pengetahuan, Sikap, Seks Bebas, RemajaABSTRACTBackground: Adolescents who enter the transitional age from childhood toadulthood have inadequate sex knowledge. Their attitude toward sex can bepositive or negative. The result of survey by the National Population and FamilyPlanning Agency in 2013 shows that the percentage of children aged 10-14 yearsold who did some activities to fulfill their sex drive was 4.38% and that ofchildren aged 14-19 years old was 41.8%.Objective: To investigate the correlation between free sex knowledge level andfree sex attitude of the adolescents of State Vocational High School 1 ofSukoharjo.Method: This research used the observational analytical research method with thecross-sectional approach. The samples of research were 185 and were taken byusing the probability sampling technique and the proportional sampling technique.The data of free sex knowledge level and attitude were collected throughquestionnaire. They were analyzed by using the Chi-square test.Result: 77.30% of the adolescents had good free sex knowledge level, and the rest22.70% had moderate free sex knowledge. In addition, 68.10% of the adolescentshad a negative attitude toward free sex, and the rest 31.90 % had a positiveattitude toward free sex as indicated by the correlation between the two variablesin which the p-value was = 0.000 (P < 0.05).Conclusion: Good knowledge could show negative and positive attitudes towardfree sex.Keywords: Knowledge, attitude, free sex, adolescents