Aim: The aim of this study was to investigate the stability of motor problems in a clinically referred sample of children with, or at risk of, autism spectrum disorders (ASDs), attention-deficit-hyperactivity disorder (ADHD), and/or developmental coordination disorder (DCD). Method: Participants were 49 children (39 males, 10 females; mean age 5y 6mo, SD 10mo) with various developmental problems, a Movement Assessment Battery for Children (M-ABC) score on or below the 15th centile, and an IQ of 70 or more. Sixteen children were at risk of developing ADHD, 15 children had a diagnosis of, or were at risk of developing ASD, and 18 children had neither diagnosis. Children were reassessed 2 to 3 years later. Results: At follow-up (mean age 7y 11mo; SD 1y), the mean M-ABC score was significantly increased, and in 22 children was no longer below the 15th centile. A general linear model to compare the difference in M-ABC scores in the three groups of children demonstrated a significant difference between groups (p=0.013), with the age at the initial assessment as a significant covariate (p=0.052). The group of children with or at risk of ASD showed less improvement in motor performance. Interpretation: Motor problems among preschool age children are not always stable, but appear to be so in most children with ASDs.