The aim of this study is to evaluate the transverse arch dimensions and compatibility of Howes orthodontic cast analysis with Turkish Populaton. The material consisted of dental casts lateral cephalograms of 55 Class I patients (25 male, 30 female) aged between 18 – 26 years. No subject had any history of systemic disease and nor had undergone prior orthodontic treatment. Original Howes orthodontic cast analysis was applied on the study casrs and cephalograms. 4 milimetric and 3 proportional parameters were used for this analysis. Tooth material, left and right first bicuspid coronal arch width and the transversal basal width were measured on the dental casts in maxillary and mandibular arches. Maxillary and mandibular basal arch lengths were measured on the cephaligrams. The ratios of first bicuspid coronal arch width, basal arch width and basal arch length to tooth material were measured. Statistical analysis of the data was evaluated with student t test. No statistically significant differences were recorded in first bicuspid coronal arch widths and basal arch widths in both maxillary and mandibular arches. Maxillary and mandibular tooth materials were found significantly greater than Howes analysis standards, respectively p < 0.05, p < 0.001. The ratio of basal arch width to tooth material in maxillary arch was significantly lowerthan Howes standards (p < 0.05). The ratio of basal arch length to tooth material in maxillary arch significantly higher than Howes standards (p < 0.001). Maxillary basal arch length and the ratio of this parameter to tooth material were significantly higher than Howes standards (p < 0.001). Mandibular basal arch length and the ratio of this parameter to tooth material was significantly lower than Howes standards, respectively p < 0.01 , p < 0.001 . Howes orthodontic cast analysis was found applicable in Turkish population except for the tooth material and basal arch lengths.