Abstract: Introduction: Childhood psychosis is a rare disorder with much contorversy between studies investigating its clinical features and premorbid function. Data concerning early onset non-affective psychosis is still lacking. Aim: The aim of this study was to describe socio-demographic data, early development, pre-morbid function and clinical characteristics of children presenting with early onset non-affective psychosis. Methods: Forty two Saudi patients with child and adolescent onsent psychosis diagnosed according to DSM-IV criteria were assessed using Schedule for Affective Disorders and Schezophrenia for School Aged Children Present and Lifetime Version (K-SADS-PL) and positive and negative symptom scale (PANSS). Developmental aspects and premorbid function were assessed by General Developmental Scale (GDS), Childhood Behavioral Sacle (CBS) and Premorbid Adjustment Scale (PAS). All data were subjected to statistical analysis. Results: The sample included 27 patients diagnosed with schizophrenia, 10 with psychotic disorrder not otherwise specified and 5 with acute psychotic episode. 61.9% of the sample had gradual onset and 38.1% had acute onset. The mean age of onset was 12.3+-3.8. Negative symptoms were more manifested than positive symptoms among the whole sample. The most frequently reported positive symptoms were hallucinations (95.2%). Psychological disturbances were relatively common as as disturbed sleep (81%), apetite disturbances (28.6%) and impaired sphincter control (14.3%). All schizophrenic and non-schizophrenic children were similar in having impairment in early development and premorbid functions that were significantly correlated with more negative symptoms and younger age of onset. Conclusion: The developmental and premorbid impairments are more emphasized in children with early onset non-affective psychosis and significantly influence the clinical presentation.