Background: Genetic polymorphisms in the TGF-beta 1 gene were shown to interfere with the transcriptional activity of the TGF-beta 1 gene, and this influences the production, secretion or activity of the TGF-beta 1 growth factor. Transforming growth factor-beta 1 (TGF-beta 1) gene polymorphism is associated with risk of inflammatory diseases. Objectives: The aim of this study was to evaluate TGF-beta 1 gene polymorphisms in a Turkish population with different periodontal diseases and to investigate the association between TGF-beta 1 genotype and clinical periodontal parameters. Methods: A total of 134 subjects were included in this study. Genomic DNA was isolated from 51 patients with chronic periodontitis (CP), 43 with generalized aggressive periodontitis (G-AgP) and 40 healthy controls. Three TGF-beta 1 gene polymorphisms were identified by PCR-RFLP and MS-PCR at positions +915G/C, Thr263Ile and 713/8delC. Probing pocket depth (PPD), clinical attachment loss (CAL), plaque accumulation (plaque %) and bleeding of probing were obtained. Chi-square, Mann-Whitney U test and logistic regression analysis were used. Results: There was a slightly significant difference in +915C positive genotype distributions between CP and control groups (OR: 2.46, CI: 1.010-6.005, p = 0.047). No significant differences were present between G-AgP and controls in +915C positive genotype. Thr-263Ile and -713/8delC genotype distributions were not different between study groups. There were significant differences in PPD and CAL scores between +915C positive and negative CP patients. Conclusion: These findings suggest that the TGF-beta 1 (+915C) polymorphic allele might be associated with chronic periodontitis in the Turkish population. (c) 2006 The Canadian Society of Clinical Chemists. All rights reserved.