The hypertension that caused by pregnancy is preeclampsia. Preeclampsia was the most important cause of death in pregnancy in UK, USA and Nordic countries. Preeclampsia also made the disturbance of uteroplacenta distribution. It could cause the low birth weight infant. In the pattern of the diseases which cause the death, showed that the first cause of the neonatal death in 0 - 7 days age was preterm and low birth weight (35%), then asphyxia (33,6%). The study was conducted to investigate the relation between severe preeclampsia and low birth weight incident. The researches used an analytic retrospective by seeing the medical record and used the Chi-Square Crosstabs Test for statistic test. The subjects was 90 pregnant women which has been born their babies in RSUP DR Sardjito Yogyakarta which 54 women have severe preeclampcia during pregnancy, 23 women have mild preeclampcia and 13 normally The result from the statistic with Chi Square Crosstabs Test showed that the p value = 0,045. The p value < 0,05 was show that there was relation between the severe preeclampcia and low birth weight incident. From the research also known that the highest frequency of low birth weight was in pregnant women with severe preeclampsia (32,3%).