This study was carried out to determine the prevalence of intestinal parasitic infections  among patients of psychiatric hospital Rumuigbo, Rivers State, Nigeria between June to September, 2017. Stool specimen were collected and analyzed from 203 patients for ova, larvae or cysts of intestinal parasites using direct wet mount and formol-ether concentration techniques. Of these, 78 (38.4%) were infected. Five parasitic infections were identified of which Ascaris lumbricoides had the highest prevalence (39.7%). Others included hookworm (8.4%), T.trichuria (4.4%) and 2 protozoans: Entamoeba histolytica (7.4%) and G. lamblia (3.0%). The occurrence of these parasites varied significantly (p< 0.05). Patients suffering from Schizophrenia had the highest prevalence of infection 33 (78.6%) followed by patients with Substance Abuse Disorder 11(37.9%), while the least prevalence was found among patients suffering from Anxiety disorder. Parasitic infection was most frequent among patients aged 18-27 years and higher among males 45 (47.9%) than the females 33 (30.3%).Prevalence of these parasitic infections varied significantly among sexes and age groups. This study has documented a higher prevalence of intestinal parasite amongst the mentally challenged in our society, re-emphasizing the need for intermittent de-worming among all the patients.