Objective: This study aimed to assess the relationship between smartphone usage time and postural alignment in teenage university students and the associated factors. Methods: We carried out a cross-sectional study with 133 teenage university students (18-19 years old) between April and November 2018 in Fortaleza, Ceará, Brazil. Questionnaires were used to collect information on socioeconomic status, health conditions, smartphone usage time and level of physical activity. The alignment of the

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... rvical region was assessed using photogrammetry in anatomical position and while texting on the smartphone. Horizontal alignment of the head (HAH), horizontal alignment of the acromion (HAA) and vertical alignment of the head (VAH) were measured. Bivariate and multivariate analyses were performed to check for factors associated with smartphone usage time (>6 hours a day). Results: There were higher rates of girls (66.9%; n=89), people in the lower social class (71.4%; n=95), frequent drinkers (66.9%; n=89), people who complained of headache (83.5%; n=111) and people who used smartphones for more than 6 hours a day (72.9%; n=97). The multivariate analysis showed an association of smartphone usage time (>6 hours a day) with cervical anteriorization, estimated by measuring the VAH (OR=1.053; p=0.007 – left side), female gender (OR=2.729; p=0.046), frequent drinking (OR=2.636; p=0.038) and complaint of headache (OR=5.617; p=0.002). Conclusions: There was a high percentage of adolescents who excessively used smartphones for more than 6 hours a day. Prolonged smartphone use was associated with female gender, alcohol consumption, headache and changes in cervical alignment.