The largest study on the effectiveness of leucovorin (folinic acid) in the treatment of autism in children was withdrawn from the European Journal of Pediatrics due to data inconsistencies and statistical problems.[1][2] The study involved 77 autistic children aged 2-10 and was published in September 2024.[1][3] This was a randomized, double-blind, placebo-controlled trial where the folinic acid group (2 mg/kg/day, max. 50 mg/day) for 24 weeks showed a reduction in CARS symptom severity versus placebo (p < 0.001).[3] Both groups received standard care including ABA therapy and sensory integration; 39 children completed follow-up in the folin group and 38 in the placebo group.[3] High titers of anti-folate receptor autoantibodies were present in 32/40 children in the folin group and 33/40 in the placebo group (p = 0.78), while improvement in CARS was more pronounced in the folin group with high titers (p = 0.03).[3] After reviewing the data, the journal was unable to replicate the results and therefore lost confidence in their validity; two authors agree with the retraction, four did not respond.[1] No adverse effects have been reported.[3] The authors are preparing a revised version of the article.[1]