OBJECTIVE Standard deviation score or Z-score reference charts are used in some countries in preference to percentile charts and are considered as better tools in assessing children with measurements outside the accepted limits of normality. Growth data for Istanbul children have previously been reported as percentiles; hence, the aim of this study is to present these data in Z-score reference tables. Data on secular trend in height in Turkish children will also be presented. METHODS Height and weight data based on a total of 11 664 height and 11 655 weight measurements in 1100 boys and 1020 girls between 6 and 18 years of age obtained by biannual visits to schools were analyzed. All children came from well-to-do families and were all healthy. All measurements were made by two trained technicians. The LMS method was used in the analyses. The results were expressed as Z-score values for age. RESULTS Heights of the boys and girls in all age groups were close to the updated USA growth references and showed an upward trend from previous data on Turkish children. CONCLUSIONS Height growth in Turkish school-age children of high socioeconomic level conforms to the updated growth data for USA children and also shows a secular trend. The data also point to the importance of updating local growth data periodically.