La fatigabilidad cognitiva, entendida como la dificultad para mantener un rendimiento óptimo durante una tarea sostenida, es una medida objetiva de la fatiga en personas con esclerosis múltiple (PcEM). Este estudio tuvo como objetivos comparar la fatigabilidad cognitiva entre PcEM y controles sanos (CS), y analizar su asociación con variables clínicas, cognitivas y demográficas. Se realizó un estudio transversal con 140 PcEM y 50 CS. Se aplicaron instrumentos clínicos (EDSS, FSS, BDI-II) y cognitivos (BICAMS, PASAT, SDMT, fluidez verbal, test 7/24). La fatigabilidad se calculó a partir de la diferencia de rendimiento entre la primera y la segunda mitad del PASAT y SDMT. Se realizaron pruebas comparativas y un modelo de regresión lineal (p <. 05). Los grupos no presentaron diferencias significativas en edad ni educación. Se hallaron diferencias estadísticamente significativas en la fatigabilidad medida por el SDMT (p =. 007), siendo mayor en las PcEM. El análisis de regresión indicó que el género fue un predictor significativo de la fatigabilidad medida por el PASAT (p =. 017, ß = 0.206). No se hallaron asociaciones entre la fatigabilidad medida por SDMT y otras variables. Las PcEM mostraron mayor fatigabilidad cognitiva que los controles, y el género podría influir en dicha fatigabilidad. Palabras clave Fatigabilidad cognitiva - Fatiga cognitiva - Evaluación cognitiva - Esclerosis múltiple ABSTRACT COGNITIVE FATIGUE IN MULTIPLE SCLEROSIS: AN OBJECTIVE MESURE Cognitive fatigability, understood as the difficulty in maintaining optimal performance during a sustained task, is an objective measure of fatigue in people with multiple sclerosis (PwMS).This study aimed to compare cognitive fatigability between PwMS and healthy controls (HC), and to analyze its association with clinical, cognitive, and demographic variables. A cross-sectional study was conducted with 140 PwMS and 50 HC. Clinical (EDSS, FSS, BDI-II) and cognitive (BICAMS, PASAT, SDMT, verbal fluency, 7/24 test) instruments were applied. Fatigability was calculated based on the difference in performance between the first and second halves of the PASAT and SDMT. Comparative tests and a linear regression model were performed (p <. 05). No significant differences were found between groups in terms of age or education. Statistically significant differences were found in fatigability measured by the SDMT (p =. 007), with higher fatigability observed in PwMS. Regression analysis indicated that gender was a significant predictor of fatigability measured by the PASAT (p =. 017, ß = 0.206). No associations were found between fatigability measured by the SDMT and other variables. PwMS showed greater cognitive fatigability than controls, and gender may influence this fatigability. Keywords Cognitive fatigability - Cognitive fatigue - Cognitive assesment -