Abstract: Mild or severe preeclampsia is responsible for about 70% of hypertensive disorders observed during pregnancy and 24 h urine collection is a gold standard for diagnosis of preeclampsia. This study was performed to determine whether the gold standard of 24 h urine protein value in pre-eclampsia can be substituted with 8 or 12 h urine protein values and to evaluate the effect of ambulation and immobilization on amount of protein excretion. A cross sectional study was conducted on 40 women with pre-eclampsia (BP≥140/90 mmHg), who referred to the Department of Obstetric and Gynecology, Imam Khomeiny hospital in Sari, Iran from April 2005 to September 2005. Positive urinary strip for protein of at least 1+ samples were collected over 24 h in subsequent periods: the first 8 h and the next 4 h and remaining 12 h urine, in separate containers. The correlation between groups was determined by Pearson`s correlation. A total of 40 women were recurited in this study of which 36 had completed urine collection. A total of 21 had mild proteinuria, 5 had severe proteinuria and 10 had no proteinuria. There was significant correlation between the 8 or 12 h (day) and 12 h (night) with 24 h urine protein. Total protein values of 8 and 12 h (day) and 12 h (night) samples, positively correlated with values of 24 h samples in pre-eclampsia and could be substituted for assessment of proteinuria instead of 24 h urine collection in women with pre-eclampsia, as a simpler, faster and cheaper method for diagnosis of pre-eclampsia. And ambulation and immobilization in preeclamptic patients has not any effect on protein excretion.