There is a dearth of comprehensive studies on comorbidities associated with intellectual disability (ID) in developing economy countries. This prospective study reports the prevalence of common comorbidities observed in a cohort of children with ID presenting to a regional medical center in Northern India. Subjects were drawn from the first three children between 6 months and 15 years of age presenting with complaints of developmental delay or mental dullness on one day a week at a pediatric outpatient unit and at the pediatric neurology clinic of a university teaching hospital. All potential subjects were tested for global developmental delay or ID by validated tests, and then the children were assessed for a set of predefined comorbid conditions, including epilepsy, cerebral palsy, microcephaly, impaired vision or hearing, feeding disorder, malnutrition, constipation, squint, drooling, violent behavior, autism, and attention deficit hyperactivity disorder (ADHD). The prevalence of comorbidities was found to be high, and it increased with severity of ID, except for ADHD, autism, and violent behavior, which decreased. Comparisons between children with and without cerebral palsy showed that most conditions were more common in children with cerebral palsy (in particular, epilepsy and constipation). A high prevalence of neurologic and medical comorbidities was seen in children with ID in Northern India, which underlines the need for a multidisciplinary approach to their identification and treatment.