Objective: growth and development of the anatomic region where the Eustachian tube (ET) is located are associated with the parameters related to other parts of the craniofacial skeleton (CFS). It has been suggested that ET dysfunction is as an important factor in pathogenesis of otitis media in childhood which is associated with its postnatal growth and development process. The purpose of this study was to evaluate associations of length of the ET with various craniofacial parameters. Methods: on lateral cephalometric radiographs of 50 Japanese adult (25 male and 25 female), the dimension of the region where the ET is located ('length of the ET') and 22 (15 linear and seven angular) craniofacial parameters were measured by using a digitiser and computer. Correlation and regression analyses were performed between this dimension and other craniofacial parameters. Results: it was found that the dimension of the region in which the ET is located ('length of the ET') was associated with many craniofacial parameters belonging to different subunits of the CFS. However, the stepwise regression analysis showed that total cranial base length, posterior upper face height and maxillary depth had determinative effects on this dimension. Conclusion: development of the ET was associated with development of the cranial base and nasomaxillary complex. Therefore, it could be hypothesised that any cessation or aberration in these parts of the CFS cause corresponding imbalances in the ET, which may predispose to otitis media. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.