Very few studies have investigated the development of visual search of aligned stimuli in relation to normal reading acquisition and in developmental dyslexia. In this study we used a new computerised experimental task which requires a visuo-motor response (RT) to a target appearing unpredictably in one out of seven different spatial positions on a horizontally aligned array of 18 geometrical figures. The aims of the study were to investigate: 1) the visual scanning development in normal children from pre-school to school age; 2) whether visual scanning performance in kindergarten children could predict reading acquisition; 3) the visual scanning abilities in a group of developmental dyslexic children. The main results were: 1) a significant decrement of RTs with age and a progressive increase of the left-to-right gradient with reading experience; 2) visual scanning abilities in kindergarten proved to be a good predictor of reading acquisition; 3) dyslexics were slow scanners and did not present the left-to-right strategy typical of normal readers. The results support the hypothesis of a relationship between visual scanning and reading abilities.