For the diagnosis of patients with growth disorders, visual inspection and the measurement of body segments may provide important information. The most commonly used method is the assessment of the sitting/standing height (SH/SH) ratio and its comparison to aged matched controls.To establish the normal values of the sitting/standing height ratio in a normal Aragonese population from birth to 18 years old.Longitudinal study from birth to 18 years old. Length (up to 3 years old), standing height (as of 2 years old) and sit-ting height were recorded. Percentiles for sitting/ standing height ratio were determined.The study included 165 male children and 167 female children. The values of the sitting/standing height ratio decrease from birth both in males and females (0.656 and 0.647, respectively) until the onset of puberty (0.514 and 0.519); and later start to slightly increase until reaching the definitive adult ratio (0.52 and 0.53, respectively).Sitting/standing height ratio values are presented in normal male and female children up to 18 years old. This ratio decreases from birth to puberty and then slightly increases until reaching the final adult ratio.