RESULTS: No significant differences existed between the groups with pre-eclampsia prior to randomization. Compared to the gravid control group, women with pre-eclampsia did not reveal significantly depressed levels of serum arginine, but did reveal significantly increased serum levels of ET, cGMP and ADMA prior to delivery. Despite a significant increase in serum arginine levels due to treatment, no differences were found in the levels of NO, ET, cGMP or ADMA between the two groups with pre-eclampsia. Further, there were no significant differences in any of the primary outcome measures with both groups demonstrating equivalent improvements in both blood pressure and proteinuria.