BACKGROUND The use of a 24-hour urine collection to evaluate protein excretion in a woman with suspected pregnancy-induced hypertension (PIH) is cumbersome, time consuming, and subject to improper collection. Our purpose was to determine the correlation of the protein/creatinine ratio of a single voided urine specimen to the 24-hour urine collection for total protein in the range of zero to 1000 mg protein per 24 hours. METHODS Single voided urine specimens and 24-hour total urine protein collections were ordered for 66 consecutive women admitted to an antepartum unit for suspected PIH. The correlation of the protein/creatinine ratio of the single voided specimen with the 24-hour urine protein excretion was calculated. RESULTS Forty-one sets of data with a 24-hour urine protein less than 1000 mg per 24 hours were obtained. The correlation of the single voided protein/creatinine ratio to the 24-hour total protein was 0.80 (P<.001), with a regression equation of (protein/creatinine)=0.81X(24-hour protein)-0.011. No single protein/creatinine ratio cutoff was ideal to distinguish between significant and insignificant proteinuria; however, a ratio less than .15 efficiently ruled out significant proteinuria [corrected]. CONCLUSIONS We conclude that the protein/creatinine ratio of a single voided urine specimen may have a role in the management of ambulatory women with suspected PIH, although further study is needed. The main potential benefit of this method is that in institutions where women with suspected PIH are hospitalized, women with insignificant proteinuria may be identified within a matter of hours and their follow-up care handled on an outpatient basis.