Introduction: Epidemiological data on gingivitis in children are important for understanding the natural course of the disease, identifying its risk factors, and predicting its time trends. The objective of this study was to evaluate the prevalence and severity of gingivitis among 6-and 12-year-old school children in Dhamar city, Yemen. Materials and methods:A total of 663 children (310 children of 6 years old and 353 children of 12 years old) were examined from 10 public primary schools. Gingival health status was assessed using the plaque index (PI), calculus index (CI), and gingival index (GI) on the six Ramfjord teeth. The latter index was used to categorize gingivitis severity at the subject level. Data were analyzed using independent t-test, chi-squared test, and Spearman's correlation. A p-value of < 0.05 was considered significant.Results: Both age groups had high mean of PI and GI with nonsignificant difference. The 12-year-old children had calculus deposits much higher than the 6-year-old group with significant difference. There was a significant correlation between age and gender of the whole sample with CI [(odds ratio, OR = 1.65, p = 0.003) and (OR = 0.74, p = 0.05) respectively]. Most of the participants presented with gingival inflammation, which was less in 12-year-old females. Conclusion:Poor oral hygiene and mild gingivitis were highly prevalent among Yemeni school children. loss. It has been reported that marginal gingivitis begins early in childhood, increases in prevalence and severity at puberty, and then subsides slightly to the remainder of the second decade of life.