Purpose of investigation: To develop a nomogram for estimating nasal bone length (NBL) at 11⁺⁰- 13⁺⁶ weeks of gestation in 554 consecutive cases and to determine the value of NBL measurement in screening for chromosomal abnormalities. Materials and Methods: NBL and crown-rump length (CRL) were examined in 554 fetuses at 11⁺⁰-13⁺⁶ weeks’ gestation. A nomogram for NBL was developed with data from 479 healthy fetuses in which fetal profile examination was possible. Reference values, including percentiles, were calculated for each gestational age. Result: A linear correlation was noted between CRL and NBL in healthy fetuses at 11⁺⁰-11⁺⁶, 12⁺⁰-12⁺⁶ and 13⁺⁰-13⁺⁶ weeks of gestation. Mean NBL was 2.18 ± 0.53 mm, 2.46 ± 0.45 mm, and 2.91 ± 0.55 mm in healthy fetuses, for these time frames, respectively. NBL increased significantly with CRL from respective means of 2.26 ± 0.43, 2.60 ± 0.48, 2.77 ± 0.43, and 3.16 ± 0.52 mm at 45 - 54.9, 55 - 64.9, 65 - 74.9, and 75 - 84 mm. Conclusion: The authors developed a NBL nomogram with data from normal, healthy Turkish fetuses at 11⁺⁰-13⁺⁶ weeks of gestation. These reference ranges may prove useful in prenatal screening and diagnosis of syndromes known to be associated with nasal hypoplasia.