Data from 49 men and 48 women included in the Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study in Perth, Western Australia, were analyzed. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were positively correlated (p less than 0.01) with urine sodium, creatine, taurine, histidine, and 3-methyl histidine but not with calcium, magnesium, or potassium. SBP was related (p less than 0.01) with body mass index (BMI). Urine nitrogen, creatinine, and amino acids correlated (p less than 0.001) with each other and with urine sodium, potassium, calcium, and magnesium. Urine magnesium correlated (p less than 0.001) with urine calcium and potassium; urine calcium was not related significantly to urine sodium or potassium. In backwards multiple regression with data from urine collections, SBP was significantly related only to urine sodium (11.9% of variance explained). If alcohol was included as an independent variable, reducing the number of valid cases because of missing values, both alcohol and urine sodium were significant in regression (19.9% of variance explained). In men, DBP was significantly related to BMI and the ratio of 3-methylhistidine to creatine (23.7% of variance explained). For DBP in women, urine sodium was the only variable needed in regression (58.4% of variance explained). Interpretation must be cautious, because these analyses are based on relatively few cases and on single 24-h urine samples. The data are in keeping with suggestions that obesity, alcohol consumption, a meat diet, and sodium intake are important factors predisposing to elevation of blood pressure.