This study investigates schoolchildren s linguistic abilities in processing high-cost linguistic structures. It focuses on the possible effects of school closure due to the COVID-19 pandemic on the performance of tasks involving high-cost processing structures. The linguistic performance of children from a public school in Rio de Janeiro was compared at two different moments: immediately after the reopening of schools in 2022, after their closure due to the COVID-19 pandemic, and one year after the easing of social isolation, in 2023. One hundred students, with an average age of 9.5 years and 8.8 years, without prior diagnosis of language problems, were tested using the syntactic module of the MABILIN battery (Language Skills Assessment Modules), with a view to screening for language difficulties, such as those suggestive of DLD (Developmental Language Disorder). In 2022, 35.47 percent of the children tested presented some degree of difficulty in understanding the structures of MABILIN 1. This percentage differs considerably from what was obtained before the COVID-19 pandemic through the same battery of tests (7-9 percent), which is similar to what has been observed in different languages. In contrast, in 2023, of the total number of children who had difficulties in 2022, 61.1 percent (22) no longer had difficulties in 2023. Therefore, it is concluded that the COVID-19 pandemic may have promoted difficulties in the development of linguistic skills in schoolchildren, although there is no clear evidence of an increase in the incidence of DLD.