It has been proposed, and questioned, whether motor impairments in attention-deficit-hyperactivity disorder, combined type (ADHD-C) alone, developmental coordination disorder (DCD) alone, and ADHD-C and comorbid DCD (ADHD-C/DCD) may arise from disruption to a common set of cognitive functions and their related neural substrate. This study examined movement durations for real and imagined movements in a visually guided pointing task in 58 prepubertal children aged 8 to 12 years old with ADHD-C alone (n=14), ADHD-C/DCD (n=14), DCD alone (n=15), and an age-, sex-, and Full-scale IQ-matched healthy comparison group (n=15). There were 10 males and 4 or 5 females in each group. The DCD alone group demonstrated an inability to generate imagined movements that was not present in the ADHD-C group, with or without comorbid DCD, or healthy comparison participants. These findings add to the emerging literature characterizing intended and actual motor impairments associated with DCD alone.