Context: Gestational diabetes mellitus (GDM) is a special form of diabetes mellitus (DM) that begins or is first detected during pregnancy. Periodontal disease has been found as a risk factor for different systemic conditions, among which DM has been widely studied. Though some studies show the association between periodontal disease and GDM, others fail to observe such correlations. Aims: The present study was planned to determine the association of maternal periodontal disease and GDM. Methods: The study comprised of 40 pregnant women, of which 20 were cases and 20 were controls. All subjects underwent a laboratory screening test for GDM between 24 to 30 weeks of gestation based on the recommendation of the Obstetricians and Gynaecologists. The subjects were divided into two groups: Group A (control) and Group B (case) based on the blood glucose level of oral glucose tolerance test (OGTT), as per the criteria of ADA (2004). For the periodontal status, a full mouth periodontal examination was performed assessing the gingival index (GI), probing pocket depth (PPD), relative attachment level (RAL) and plaque index (PI) using a UNC -15 probe by a single examiner who was blinded on the diabetic status of the pregnant women. To compare the means, student’s t-test was performed. Results: GI score in women with GDM was 2.60 0.66 (range 1.05 - 3.00) whereas those without GDM 1.94 0.77 (range 1.07 - 3.00), (p<0.01). The mean PPD of control group was 2.50 ± 0.70 (range 1.38 - 3.71) mm and of case group was 3.91 ± 0.96 (range 2.42 - 5.05) mm; (p<0.001). The mean RAL of control group was 8.23 ± 1.83 (range 3.57 - 11.14) mm and of case group was 9.82 0.76 (range 8.71 - 11.25) mm; (p<0.01). The mean PI of control group was 1.42 ± 0.48 (range 0.69 - 1.97) and in case group was 2.09 0.90 (range 0.04 - 2.63); (p<0.001). Conclusions: GI, PI, PPD and RAL were more in subjects with GDM than those without GDM. Hence, GDM is associated with periodontal disease.