Although dyslexia is the most common learning disorder in children, it has not received adequate attention in Saudi Arabia. This study aimed at determining the prevalence of dyslexia among Saudi students in Grades 3–6, exploring associations between severity of dyslexia, its behavioral indicators, gender and grade, and the moderating role of grade in the relationship between severity and behavioral indicators. The sample consisted of 2848 female students and 2647 male students in Zulfi governorate, Saudi Arabia. A survey-based mixed-methods design was chosen including a structured interview with teachers and three assessments using the Diagnostic Assessment Scale for Dyslexia, the Arabic Reading Test, and the Dyslexia Behavioral Indicators Scale. Dyslexia was assessed in 5.86 % of the total sample. It was twice as prevalent among male students as among female students (6.54 % and 3.83 %, respectively). The mean score for behavioral indicators of dyslexia was also significantly higher for male than for female students. The correlation between dyslexia severity and behavioral indicators score was high and significant, with grade level as a significant moderator. We found that, for children with dyslexia in Saudi Arabia, dyslexia was twice as prevalent among male students as among female students. Early dyslexia diagnosis and intervention services are suggested to reduce the risk for reading problems. •This research yields a better understanding of the role of grade progression on the relationship between severity of dyslexia and its behavioral indicators.•This research showed that in children with dyslexia in Saudi Arabia, the dyslexia was twice as prevalent among male students as among female students.•The behavioral indictors of dyslexia were higher in male students than in female students•Correlations between dyslexia severity and behavioral indicators were higher for female than male students•The results indicate that as the student grade level increased the negative relationship between dyslexia severity and behavioral indicators of dyslexia decreased.