Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by a persistent deficit in social communication and interaction and, the presence of RRBs, interests or activities. Diagnosis of ASD relies on five key criteria (A to E) and six severity specifiers, reflecting its broad impact on daily life. One of the most prevalent symptom of ASD is sensory processing difficulties, affecting on average 90-95% of autistic individuals across all age groups. These difficulties manifest as hyper- or hyposensitivity to external stimuli and involve unusual interests in sensory aspects of the environment. One of the key brain structures involved in sensory processing is the thalamus, which is organized into distinct nuclear groups with specific roles and connectivity. Understanding the association between brain development and ASD symptoms, particularly through the mor- phology of the thalamus and its role in sensory processing, is critical for insights into ASD’s physiopathology. The association between the volume of the thalamus and its nuclear groups and sensory processing difficulties in ASD is still understudied. We speculate that any macrostructural abnormalities in the thalamus may result in a failure to properly filter or “gate” sensory inputs to the cortex. This could lead to a sensory overload scenario and sensory processing impairments, as observed in individuals with ASD. Therefore, the aim of this project was to delineate the structural characteristics of the thalamus and its nuclear groups in young boys with ASD and age-matched Typical Developing (TD) boys. We obtained MRI images from 67 boys diagnosed with ASD and 19 TD boys from 67 boys diagnosed with ASD and 19 TD boys. Using Freesurfer for automatic segmentation, we parcellated the thalamus into 25 nuclei, grouping them into five main groups and two entities: anteroventral, ventral, lateral, medial and pulvinar nuclear groups, along with the LGN and MGN. This classification highlights the diverse functions and connections of these nuclear groups within the thalamus. Sensory functioning was assessed using age-appropriate sensory profile questionnaires. The volume trajectories were compared between groups (ASD vs. TD) and subgroups (based on the sensory profile, the severity of symptoms, and intellectual functioning). The volume trajectories of the ICV, total thalamus, and its nuclear groups demonstrate a linear increase with age. No significant differences were found between the ASD and TD groups. However, significant decreases in volume growth were observed across the ICV, total thalamus, anteroventral nucleus, ventral nuclear group, LGN, and MGN in the ASD group with an Atypical Sensory Profile, compared to those with a Typical Sensory Profile. These differences are specific to variations in sensory processing performance, rather than differences in symptom severity or intellectual functioning.