Background: Estimation of urinary parameters in neonates is a useful method for identifying metabolic derangements. Objectives: A prospective, hospital-based study was designed to study the specific reference values for urinary calcium/creatinine (mg/mg) in healthy breast-fed newborns, and to evaluate the relationship between urinary calcium/creatinine, urinary phosphorus/creatinine, urinary sodium/creatinine, urinary potassium/creatinine and urinary sodium/ potassium ratios in the same group. Patients: A total of 100 infants aged between (0-28) days were enrolled in this study. They were divided into two age groups as follows: Group 1: ≤7 days of age; Group 2 infants aged between (8-28) days. Methods: Non-fasting spot urine was analyzed for calcium, phosphorus, sodium, potassium and creatinine. Results: Infants ≤7 days of age (Group 1) showed lower urinary calcium/creatinine, urinary sodium/creatinine, and urinary sodium/ potassium than those of (Group 2). The calcium/creatinine positively correlated with both sodium/creatinine and sodium/ potassium ratios in urine. Conclusion: Differences should be taken into consideration when assessing urinary excretion of these parameters for diagnostic purposes in the early and late newborn periods.