BACKGROUND Preeclampsia is a common complication of pregnancy and a major cause of morbidity and mortality of mothers and babies worldwide. This study aimed to explore what the role of calcium/creatinine ratio is in urine compared with proteinuria and uric acid in predicting preeclampsia. MATERIAL AND METHODS In this prospective case-control study, 200 pregnant women who participated in the study were consecutively divided into 3 groups: a group of 59 women with preeclampsia, 61 women with pregnancy-induced hypertension, and a control group of 80 normotensive pregnant women. A 24-h urine sample was collected for estimation of calcium/creatinine ratio and proteinuria and a blood sample for estimation of uric acid at a gestational age of 24-34 weeks of pregnancy. RESULTS The study found that the sensitivity of proteinuria as a predictor of preeclampsia was 96.6% (P=0.000) and specificity was 21.3%. The sensitivity of uric acid as a predictor was 96.6% (P=0.000) and the specificity was 48.8%; whereas for the 24-h urine calcium/creatinine ratio, the sensitivity was 87.9% (P=0.000) and the specificity 40.7%, which corresponds to a value of 0.105 (cutoff). Women with a calcium/creatinine ratio <0.105 have a higher risk of developing preeclampsia (87.9% confidence interval, P=0.000). CONCLUSIONS The role of the calcium/creatinine ratio in urine is inferior to proteinuria and uric acid in predicting preeclampsia.