Maternal factors (e.g., maternal anxiety) and infant temperament (e.g., distress to novelty) shape children’s social-emotional development. However, we know relatively little about the impact these factors have on ​infant brain​ development. This study investigates associations between maternal anxiety, distress to novelty (i.e., negative reactivity) and brain morphometry at 4-months. At 4-months, infants’ temperament was assessed by identifying distress in response to novel stimuli. Mothers completed the Beck Anxiety Inventory (BAI) to measure maternal anxiety. Within 2-weeks, high-resolution structural MRI data were acquired during infants’ natural sleep. MRI data were processed using the iBEAT (Dai et al, 2013) pipeline to obtain subcortical and cortical volume estimates. Regression analyses were conducted to investigate whether infant temperament moderated the relation between maternal anxiety and brain volume at a priori selected regions of interest, controlling for total intracranial volume. Results indicate that there was no significant interaction or main effect of temperament. However, there was a main effect of maternal anxiety in all ROIs tested. Greater maternal anxiety predicted larger hippocampus (β=.417,p<.036), amygdala (β=.429,p<.031), superior frontal gyrus (β=.410,p<.041), middle frontal gyrus (β=.411,p<.039), inferior frontal gyrus (β=.404,p<.039), dorsal anterior cingulate cortex (β=.416,p<.039) and posterior cingulate cortex (β=.407,p<.042). This study provides novel evidence that increased maternal anxiety is linked to differences in child-brain morphometry.