Lutheran High School South (LHSS) is a private Lutheran co-educational school located in Affton, an unincorporated area in St. Louis County, Missouri, in the United States. Established in 1957, the school is affiliated with the Lutheran Church–Missouri Synod. The school serves approximately 400 students in grades 9 through 12 who live in the St. Louis, Missouri area. Lutheran South, along with Lutheran High School North, belong to the Lutheran High School Association of St. Louis. LHSS is accredited by AdvancED.