Attention-deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder consisting of inattentive and/or hyperactive behaviors that is typically prevalent in childhood. There are three recognized subtypes of this disorder—hyperactive, inattentive, and combined. The current study’s purpose is to examine how the subtypes differentiate based on brain structure volume size. There have been studies on ADHD subtypes and brain structure volumes in children, but there are a number of limitations in available research that make it difficult to generalize findings. A meta-analysis was done using 8 studies that included volumetric data of ADHD subtypes (inattentive and combined) in children that was acquired through magnetic resonance imaging (MRI) techniques. Analyses were done looking at combined and inattentive type in comparison to controls and between the two groups. Further subgroup analyses were done on gender and brain regions in the two subtypes. Results show that there is a significant brain volume reduction in combined type in comparison to controls and inattentive type. There is also a significant volume reduction observed in males. The other analyses done yielded insignificant findings, although the volume reduction in inattentive type was only slightly above the cutoff of alpha (0.05). These findings help in better understanding the relations between brain volume and ADHD subtypes, but further research is still needed in this area.