AIM: To characterize the neurological and cognitive outcomes in children with antibody‐negative autoimmune encephalitis (Ab‐negative AE). METHOD: A cohort of children presenting to our institution over a 10‐year period with autoimmune encephalitis was identified by structured retrospective review of medical records. Clinical features at presentation and final follow‐up were recorded. Neuropsychological testing was performed in a subset of patients. Outcomes after Ab‐negative AE were compared with outcomes after N‐methyl‐D‐aspartate receptor antibody encephalitis (NMDARE). RESULTS: Forty‐four patients (26 females, 18 males, median age 9y 2mo [interquartile range 4y 5mo–11y 8mo], 23 with NMDARE) with a diagnosis of autoimmune encephalitis were included. Postencephalitic epilepsy was more frequent after Ab‐negative AE compared to NMDARE (61% vs 14%, p=0.002). Cognitive testing was performed in a subset of patients (n=21; Ab‐negative AE=11, NMDARE=10). Full‐scale IQ was lower after Ab‐negative AE than NMDARE (mean IQ 75 vs 92, p=0.02), primarily because of reduced verbal comprehension index (80 vs 98, p=0.01) and working memory index (77 vs 95, p=0.09). The cognitive function most commonly impaired was executive function (80% [8/10] vs 22% [2/9]). INTERPRETATION: Ab‐negative AE was associated with poorer cognitive outcomes than NMDARE at 1‐year follow‐up. Further studies are required to evaluate if immunotherapy can be optimized to improve outcome. [ABSTRACT FROM AUTHOR]