Since the nature and the level of urinary protein excretion have considerable clinical implications in the course of pregnancy, the early detection of even minor degrees of hyperproteinuria is important. Quantitation of 24-h urinary protein excretion is the only definite method of establishing the presence of hyperproteinuria, but this method shows practical failures particularly in an outpatient setting. Dipstick analysis as a screening for hyperproteinuria also lacks reliability, since the normal rate of protein excretion in primigravid pregnancy has recently been shown to be less that 150 mg per day. In this study, therefore, we propose the determination of the protein/creatinine ratio in a single voided urine sample, obtained during normal daylight activity, as a screening test for hyperproteinuria during pregnancy which can replace the quantitation of 24-h urinary protein excretion.