Introduction: Anxiety disorders in primary school-aged children negatively affect their mental health and psychological development. Available non-medical treatments for these conditions are time-consuming and expensive. In this context, eclectic therapy is a therapeutic approach that incorporates some therapeutic techniques and philosophies to create the ideal treatment. In this study, eclectic therapy consisted of art therapy and cognitive-behavioral therapy designed for children suffering from high level of anxiety in their middle childhood years. The therapy also included group guidance sessions for their mothers. The effectiveness of this intervention was examined in the study. Methods: 61 students aged 9-12 years with high levels of anxiety participated in the study. Intervention A (n = 20) consisted of 9-hour eclectic therapy for children with 3-hour group guidance sessions for their mothers. Intervention B (n = 20) consisted of 9-hour eclectic therapy for children. There was also a control group (n = 21). Results: Teacher ratings of children’s mental health difficulties and self-report ratings of anxiety disorders indicated a significant difference from pretest to posttest, revealing a large effect size between the two interventions. Higher levels of pretest scores significantly predicted higher posttest scores for all domains of anxiety and mental health difficulties. Furthermore, age, gender, mothers working a 15-hour day, mother’s educational level, parental divorce rates, parental death, and family monthly income predicted therapy outcomes. Conclusion: Results provide support for the effectiveness of eclectic art and CBT to improve children’s mental health and reduce anxiety through changing thoughts, beliefs, emotions, and behaviors that may cause fear and anxiety. Abstract (Portuguese) Introducao: Transtornos de ansiedade em escolares afetam sua saude mental e seu desenvolvimento psicologico. Tratamentos alternativos disponiveis consomem tempo e sao dispendiosos. Nesse contexto, a terapia ecletica e uma abordagem terapeutica que incorpora algumas tecnicas e filosofias terapeuticas para criar o tratamento ideal. Neste estudo, terapia ecletica consistiu de terapia artistica e terapia cognitivo-comportamental (TCC) planejada para escolares com altos niveis de ansiedade. A terapia tambem incluiu sessoes de orientacao em grupo para as maes. A eficacia da intervencao foi examinada. Metodos: 61 escolares com idade de 9-12 anos e altos niveis de ansiedade participaram do estudo. A intervencao A (n = 20) consistiu de 9 horas de terapia ecletica para criancas com sessoes de 3 horas de orientacao em grupo para as maes. A intervencao B (n = 20) consistiu de 9 horas de terapia ecletica para criancas. Houve tambem um grupo controle (n = 21). Resultados: Escores atribuidos pelos professores as dificuldades de saude mental das criancas e escores de ansiedade autoaplicados indicaram diferencas significativas entre resultados pre-teste e pos-teste, revelando grande tamanho de efeito entre as duas intervencoes. Escores pre-teste maiores foram preditores significativos de escores pos-teste mais altos para todos os dominios de ansiedade e dificuldades de saude mental. Idade, genero, maes trabalhando 15 horas/dia, nivel educacional da mae, indice de divorcio, morte de um dos pais e renda familiar mensal foram preditores de desfechos da terapia. Conclusao: Os resultados sugerem a eficacia de arte ecletica e TCC para melhorar a saude mental de criancas e reduzir a ansiedade atraves de mudanca em pensamentos, crencas, emocoes e comportamentos que possam causar medo e ansiedade.