The aim of this study was to investigate whether grey matter densities (GMD) in the brain associate with speech disfluency in 120 (65M, 55F) 5-year-old children. Speech disfluency, which was quantified via audio recordings, was measured as a continuous variable, covering a broad spectrum of disfluencies observed in a sample of children participating in the FinnBrain Birth Cohort study. Structural magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) of the whole brain was utilised to examine the associations between GMD and speech disfluency. We found negative associations between stuttering-like disfluencies (SLD) and GMD in the middle frontal gyrus and cerebellum in the left hemisphere, and the precuneus and superior frontal gyrus in the right hemisphere (p < .005, FDR corrected). For other types of disfluencies (OD), a statistically significant negative correlation was found with GMD in the left postcentral and right middle temporal gyrus (p < .005, FDR corrected). In general, boys had higher levels of SLDs and ODs in comparison to girls but interactions by sex were not statistically significant. Our findings largely corroborate existing literature while also offering new insights into the increased involvement of the precuneus and cerebellum in speech fluency, thereby enriching prior research in the field of speech motor control and language models.Negative association of SLD with GMD in the middle frontal gyrus and cerebellum in the left hemisphere, and the precuneus and superior frontal gyrus in the right hemisphere for 5-year-old children; the colour bar represents the z-scores of the SLD cluster values