The urine urea nitrogen/urine creatinine excretion ratio (UUN/UCr) of a "spot" urine specimen obtained approximately 5 hours after the last meal of the day can be used to accurately calculate the urinary urea excretion for the previous 24-hour period. Because UUN excretion is largely determined by dietary intake of protein nitrogen, this method can be used to estimate dietary protein intake for the previous 24-hour period. Strategies for using this simple method for inexpensively and continuously monitoring dietary protein intake are discussed.