Introduction: Gestational diabetes mellitus (GDM) is defined as carbohydrate intolerance of varying degree of severity with onset or first recognition during pregnancy. Objective: To find the prevalence of GDM in a selected maternity centre in Kanyakumari district. Materials and methods: Antenatal mothers (n=216) of 24-28 weeks gestational age attending the obstetrics and Gynaecology outpatient department (OPD )from May 2016 to April 2017 underwent 75gm oral glucose tolerance test (OGTT) irrespective of their last meal. Antenatal mothers with a history of diabetes were excluded from this study. Blood samples were drawn at 2 h and plasma glucose was estimated by GOD-POD method and the prevalence of GDM was computed based on Diabetes In Pregnancy Study group India (DIPSI) criteria. Result: Among the 216 women screened 36 (16.7%) had GDM and among risk factors, higher BMI and Age was significantly associated with GDM.