The aim of the present study is to examine attentional costs (inhibition) in covert visual attention in a group of acutely ill adolescents with schizophrenia without long histories of neuroleptic treatment. Variations in reaction time were analyzed for possible age and sex differences. Adolescents with schizophrenia (n = 19) were compared to a group of ADHD subjects (n = 20) and a group of normally functioning adolescents (n = 30) on a measure of covert visual attention. The results support a hypothesis of abnormally rapid disengagement (reduced costs) in male adolescents with schizophrenia. Such an abnormality has also been found in adults with chronic schizophrenia. Whether this holds true for both sexes of adolescents with schizophrenia or is restricted to male subjects cannot be answered with certainty due to the small number of females with schizophrenia in our sample. Our findings indicate, however, that there are some general sex differences and some specific sex differences related to covert visual attention in adolescents with schizophrenia.