Background: Pregnancy is a major change that occurs in the life of a woman in which the woman will experience many changes in her psychological and physiological. Physiological changes experienced by trimester II and III pregnant women are lower back pain. Complaints in the form of lower back pain can make the sleep of pregnant women disturbed and cause the quality of maternal sleep to be bad. Insufficient sleep needs for pregnant women can have a bad impact on the mother and pregnancy namely hypertension that can lead to abortion. Objective: This study was to determine the relationship between lower back pain and sleep quality in pregnant women. Method: This research is a quantitative research. The study design used correlational with a cross sectional approach. The total population of pregnant women at the Kasihan I Bantul Health Center is 509 people. The samples were 96 trimester II and third trimester pregnant women using purposive sampling technique. The research instrument used the Pittsburgh Sleep Quality Index (PSQI) questionnaire to measure sleep quality and the Numeric Rating Scale (NRS) to measure pain levels. The statistical test using spearman rank. Results: The study shows that the majority of respondents experiencing low back pain in the mild category is 46 people (47.9%) and most respondents experiencing a poor sleep quality is 85 people (88.5%). The results have p value of 0.008 (p <0.05) which means that there is a significant relationship between low back pain and sleep quality in pregnant women. Conclusion: There is a relationship between lower back pain and sleep quality in pregnant women.