OBJECTIVE: to analyze the effects of a Mindfulness-based intervention on nurse leaders' emotional intelligence and resilience. METHOD: a pilot study of a randomized crossover clinical trial. The sample (n=32) was randomized into Group A (n=18) and Group B (n=14) and evaluated at the pre-test, post-test and follow-up moments. The outcomes were assessed using the Emotional Intelligence Measure, the Connor-Davidson Resilience Questionnaire and the Five Facet Mindfulness Questionnaire, and analyzed using Generalized Linear Mixed Models. RESULTS: a total of 32 nurses with a mean age of 42.6 years old were evaluated. The analyses showed significant interactions between the effects of the group x moment factors on the Self-motivation (p=0.005), Sociability (p<0.001), Self-control (p=0.013), and Total (p=0.002) emotional intelligence skill scores; as well as on the Observe (p=0.042), Describe (p=0.008), Non-judgment (p<0.001), Act with awareness (p=0.004) and Total (p<0.001) mindfulness facets. Post-test: there was a statistically significant increase in the Sociability (p=0.009) and Self-control (p=0.015) emotional intelligence skills; as well as in the Non-judgment (p=0.022) and Total (p=0.002) mindfulness facets. Follow-up: a significant increase was observed in the Non-judgment (p=0.024) and Total (p=0.026) mindfulness facets. The "resilience" variable did not present statistical significance in the "group x moment" factor, both in the post-test and during follow-up. CONCLUSION: the Mindfulness-based intervention used proved to be effective in increasing nurse leaders' emotional intelligence and dispositional mindfulness skills. Brazilian Registry of Clinical Trials (RBR-3c62gy), registered on March 4 th , 2020, updated on September 16 th , 2022. BACKGROUND: (1) Unpublished study of a Mindfulness-based intervention with nurse leaders. BACKGROUND: (2) Positive effect on the participants' emotional intelligence and mindfulness. BACKGROUND: (3) Advances in knowledge about emotional intelligence and leadership resilience. BACKGROUND: (4) It encourages the implementation of sensitive and innovative health strategies. OBJETIVO:: analizar los efectos de una intervención basada en MÉTODO:: estudio piloto de un ensayo clínico aleatorizado cruzado. Muestra (n=32) aleatorizada en el grupo A (n=18) y grupo B (n=14), se los evaluó en el pretest, postest y seguimiento. Los resultados fueron evaluados mediante la Medida de Inteligencia Emocional, el Cuestionario de Resiliencia de Connor-Davidson y el Cuestionario RESULTADOS:: fueron evaluadas 32 enfermeras con una edad promedio de 42,6 años. Los análisis mostraron interacciones significativas de los efectos de los factores grupo vs. momento en los puntajes de las habilidades de automotivación (p=0,005), sociabilidad (p<0,001), autocontrol (p=0,013) y total (p=0,002) de inteligencia emocional; de las facetas observar (p=0,042), describir (p=0,008), no juzgar (p<0,001), actuar con conciencia (p=0,004) y total (p<0,001) de CONCLUSIÓN:: la intervención basada en OBJETIVO:: analisar os efeitos de uma intervenção baseada em MÉTODO:: estudo-piloto de ensaio clínico randomizado cruzado. Amostra (n=32) randomizada em grupo A (n=18) e grupo B (n=14), avaliados nos momentos pré-teste, pós-teste e seguimento. Os desfechos foram avaliados pela Medida de Inteligência Emocional, pelo Questionário de Resiliência Connor-Davidson e pelo Questionário das Cinco Facetas de RESULTADOS:: foram avaliadas 32 enfermeiras com idade média de 42,6 anos. As análises mostraram interações significativas dos efeitos dos fatores Grupo x Momento nos escores das habilidades de automotivação (p=0,005), sociabilidade (p<0,001), autocontrole (p=0,013) e total (p=0,002) de inteligência emocional; das facetas observar (p=0,042), descrever (p=0,008), não julgar (p<0,001), agir com consciência (p=0,004) e total (p<0,001) de CONCLUSÃO:: a intervenção baseada em