Objective: Cognitive developmental delay is a picture of the group of early-onset chronic diseases that affect 1.5-10% of children. Autism spectrum disorders are neurodevelopmental diseases with a genetic basis and abnormal brain development, characterized by disorders in areas that make up interpersonal relationships, such as communication, social cognition, and processing of emotional signals. Immune system dysfunction is thought to play a role in the pathogenesis of some neurological disorders, including autism. Progranulin is thought to be a regulator of the innate immune response. The purpose of this study was to look at plasma levels of progranulin, an anti-inflammatory neurotrophic factor, in children with autism spectrum disorder and cognitive developmental delay. Materials and Methods: The study was conducted on 52 children who were patients and 35 healthy children. Of the 52 children of the patient group, 32 were diagnosed with CDD and 20 were diagnosed with cognitive developmental delay–autism spectrum disorder. Serum progranulin concentrations were measured using a human-specific sandwich enzyme-linked immunosorbent assay. Results: Serum progranulin concentration was statistically lower in the patient group (110.746 ± 26.04) than in the healthy control group (137.346 ± 30.02). There was a statistically significant difference between the groups in levels of serum progranulin (P=.000). Receiver operating characteristic analysis was performed to evaluate the potential of progranulin as a biomarker to distinguish patients with cognitive developmental delay–autism spectrum disorder from healthy children. It detected a moderate area under the curve (0.743 ± 0.06) value and a more significant P value for progranulin (P=.000). Conclusion: Progranulin deficiency in patients with autism spectrum disorder–cognitive developmental delay may result in decreased neurotrophic support for many years, with cumulative damage associated with unregulated inflammation that may play a role in autism spectrum disorder–cognitive developmental delay. We believe that low progranulin levels could be a biomarker for autism spectrum disorder–cognitive developmental delay.