Background This cross-sectional study aimed to assess the levels of LL-37 in the gingival crevicular fluid (GCF) and saliva in non-smokers and smokers with stage III and IV periodontitis. Materials and Methods: 60 participants in a sample from Egyptian patients seeking dental treatment at the Diagnostic Center, Faculty of Dentistry, Cairo University. Periodontal examination involving Pocket depth, clinical attachment level, gingival recession depth, bleeding on probing and plaque index were measured using a manual UNC periodontal probe