The serum and urine polyamines putrescine, spermidine, and spermine were measured in 112 normal subjects from 0 to 70 yr of age, and in three groups of short children from 7 to 20 yr: 21 growth hormone (GH) deficient patients, 20 normal variant short stature children, and 9 girls with 45, X Turner's syndrome. Urine polyamines were expressed as micromoles per gram of creatinine or per kilogram body weight, and serum polyamines were expressed as nanomoles per milliliter. In normals, the three polyamines were highest in urine and serum at birth. The mean levels declined progressively with age, the rate of change decreasing with age. The mean for the normal subjects, and its 95% confidence and prediction intervals, were estimated from birth to age 70 for each serum and urine polyamine. In GH-deficient children, serum and urine values were significantly lower (P < 0.05) than the age-specific normal values (with the exception of serum spermidine and spermine), averaging 25-55% below normal. This abnormality was corrected during 1 wk of treatment with human GH. In Turner's syndrome, serum and urine values were significantly reduced (P < 0.05), averaging 35-80% below age-specific normals. GH treatment had no corrective effect. In 6 of 20 normal variant short stature children, polyamine levels were significantly (P < 0.01) subnormal, averaging 50-80% below age-specific normals in both serum and urine. Treatment with GH had no corrective effect. These data show that levels of polyamines in serum and urine are correlated with linear growth primarily during the first decade of life. Subnormal polyamine levels are generally associated with growth retardation.