Objective: To investigate factors associated with gingivitis in children aged one to 13 years with developmental disabilities. Material and Methods: A total of 408 dental records were used to recover the data. Gingivitis was measured based on the Modified Gingival Index. Other variables were also analysed: gender, age, International Classification of Diseases (ICD) code, mouth breathing, history of gastroesophageal reflux, use of psychotropic drugs, reports of dry mouth, history of asthma, use of medications to treat asthma, oral hygiene, dental caries, and filled or missing teeth in deciduous or permanent dentition. For the purposes of this analysis, the individuals were categorized as with and without gingivitis. Variables with a p-value < 0.25 in the bivariate analysis were incorporated into the logistic regression models (ICD, reflux, oral hygiene, primary tooth decay or filling, mouth breathing, dry mouth and use of psychotropic drugs). Results: We found a 14.67% prevalence of gingivitis. Individuals with mouth breathing had a 2.574-fold (95% CI: (1.113-5.950) greater chance of exhibiting gingivitis. Individuals with moderate oral hygiene had a 2.763-fold (95% CI: 1.066 to 7.160) greater chance of exhibiting gingivitis, and individuals with poor oral hygiene had a 15.029-fold (95% CI: 3.705-60.965) greater chance of exhibiting gingivitis than those with good oral hygiene. Conclusion: Moderate or poor oral hygiene and mouth breathing are factors associated with gingivitis in a group of patients with developmental disabilities at a dental service in Belo Horizonte.