Congenital disorders of glycosylation (CDG) are caused by defective glycosylation of proteins and lipids. PMM2‐CDG is the most common subtype among the CDG. The severity of PMM2‐CDG is variable. Patients often have a recognizable phenotype with neurological and multisystem symptoms that might cause early death. We report six patients from three families who are diagnosed with a clinically mild PMM2‐CDG and have normal cognitive development. All these patients had delayed gross motor skills with mild‐to‐moderate neurological findings. Cerebellar hypoplasia was detected in all siblings for whom brain MRI was performed. In 5/6 children the Wechsler Intelligence Scale for Children (WISC) showed normal cognitive development with full scale IQ scores ranging from borderline to average. Four patients were diagnosed with PMM2‐CDG at the age of 8 years or later as their neurological symptoms were quite mild and they had been able to participate in regular school programs. We report patients with p.Val231Met/p.Arg239Trp and p.Ile120Thr/p.Gly228Cys genotypes which may cause milder variants of PMM2‐CDG.