Background and Purpose Primary microcephalies are incompletely understood malformations that are often associated with developmental brain anomalies, yet it is not understood if the associated anomalies result from the microcephaly itself or from associated developmental/genetic mishaps. This study reviewed and analyzed a large number of MRI scans of children with microcephaly to determine the frequency of associated morphological findings and to assess whether these findings were associated with the severity of the microcephaly. Materials and Methods MRIs of 119 patients with clinically diagnosed microcephaly were retrospectively reviewed, focusing on the degree of microcephaly, simplification of gyri, white matter volume, abnormalities of corpus callosum, size and structure of posterior fossa contents, and myelination. Associations among the findings were evaluated using the Spearman correlation coefficient and the Fisher exact test. Results Among 7 patients with mild, 42 with moderate, and 70 with extreme microcephaly, a significant correlation was identified between a greater degree of microcephaly and both a greater degree of simplified gyration and decreased white matter volume. The severity of callosal anomaly showed a lower, but still significant, correlation with the severity of microcephaly. Degree of hypoplasia of posterior fossa structures, delay in myelination, and abnormality of basal ganglia did not correlate with the degree of microcephaly. Conclusion A strong correlation was found between the degree of microcephaly, the volume of white matter, and the presence of a simplified gyral pattern. These associations should be considered when attempting to use neuroimaging for segregation and classification of patients with microcephaly.