Pre-eclampsia and eclampsia are major causes of maternal morbidity and mortality. Magnesium sulphate is accepted as the anticonvulsant of choice in these conditions and is present on the WHO essential medicines list and the Indian National List of Essential Medicines, 2015. Despite this, magnesium sulphate is not widely used in India for pre-eclampsia and eclampsia. In addition to other factors, lack of availability may be a reason for sub-optimal usage. This study was undertaken to assess the availability and use of magnesium sulphate at public and private health care facilities in two districts of North Karnataka, India. A facility assessment survey was undertaken as part of the Community Level Interventions for Pre-eclampsia (CLIP) Feasibility Study which was undertaken prior to the CLIP Trials (NCT01911494). This study was undertaken in 12 areas of Belagavi and Bagalkote districts of North Karnataka, India and included a survey of 88 facilities. Data were collected in all facilities by interviewing the health care providers and analysed using Excel. Of the 88 facilities, 28 were public, and 60 were private. In the public facilities, magnesium sulphate was available in six out of 10 Primary Health Centres (60%), in all eight taluka (sub-district) hospitals (100%), five of eight community health centres (63%) and both district hospitals (100%). Fifty-five of 60 private facilities (92%) reported availability of magnesium sulphate. Stock outs were reported in six facilities in the preceding six months – five public and one private. Twenty-five percent weight/volume and 50% weight/volume concentration formulations were available variably across the public and private facilities. Sixty-eight facilities (77%) used the drug for severe pre-eclampsia and 12 facilities (13.6%) did not use the drug even for eclampsia. Varied dosing schedules were reported from facility to facility. Poor availability of magnesium sulphate was identified in many facilities, and stock outs in some. Individual differences in usage were identified. Ensuring a reliable supply of magnesium sulphate, standard formulations and recommendations of dosage schedules and training may help improve use; and decrease morbidity and mortality due to pre-eclampsia/ eclampsia. The CLIP trial was registered with ClinicalTrials.gov ( NCT01911494 ).