OBJECTIVE To determine the value of random urinary protein to creatinine ratio (UPCR) for diagnosis of proteinuria in pregnant women with preeclampsia. Preeclampsia is the most common complication of pregnancy and one of the main causes of maternal mortality. So, early diagnosis of preeclampsia is very important. METHODS In this cross-sectional study 66 pregnant women suspected preeclampsia at ≥24 week of gestational age and BP ≥ 140/90 mm/Hg were checked by two urine samples of 10am and 4pm to determine random UPCR, as well as a 24-hour urine sample to evaluate 24-hour protein excretion. RESULTS The result revealed that 74.2% of the studied population had significant proteinuria. There was a correlation between UPCR and 24-hour urine protein excretion. Pearson's correlation coefficient was 0.502 at 10am and 0.428 at 4pm. The best cutoff for the random urine protein to creatinine ratio at 10am was 0.470 with sensitivity and specificity equal to 87.5% and 84.2%, respectively. The best cutoff for the random UPCR at 4pm was 0.595 with sensitivity and specificity equal to 91.7% and 94.7%, respectively. CONCLUSIONS Result of 24-hour urine collection showing random UPCR is considered as an appropriate situated method for emergency time.