The aim of the study was to investigate the association between haemoglobin level & severity of chronic periodontitis. This retrospective study was carried out by analysing the patient records from June 2019 to March 2020 at Saveetha Institute of Medical & Technical sciences (SIMATS).Two forty four patients were included in the study. Parameters assessed were a)Demographic details – Patient name, Patient identity number, Age & Sex; b)Periodontal parameters – Probing pocket depth (PDD), Loss of attachment (LOA), Bleeding on probing (BOP), Severity of Periodontitis (mild, moderate & severe);c) Blood parameters - Haemoglobin levels (g/dl). Data was analysed using SPSS version 23.0. Bivariate Pearson correlation of Haemoglobin with mean PPD, mean LOA & mean BOP score were calculated. Mean Hb was compared with severity of periodontitis using ANOVA. A total of 244 patients were included in the study. The mean age of the study sample was 40.42 (±11.38). Females constituted about 58.06%, whereas males constituted 41.4% of the study sample. Majority of the population had severe periodontitis (64.76%), followed by mild periodontitis (18.03%) & moderate periodontitis (17.21%). The mean haemoglobin level in severe periodontitis (13.35g/dl) is higher when compared to moderate and mild periodontitis (13.30g/dl & 13.18g/dl respectively). Mean PPD was 5.24 mm, mean LOA was 4.6 mm & mean BOP score was 0.98. Association between mean CAL and mean haemoglobin levels was positive and statistically significant with a p value of 0.012. Mean Hb level was not significantly different with varying severity of periodontitis (p = 0.86). Thus, from this retrospective study, there was no significant association between haemoglobin levels and severity of periodontitis.