Precursor B-ALL (BCP-ALL) is associated with a good outcome in children. Cytogenetics is one of the gold standards for risk stratification for treatment that has contributed to improved survival. Although in T-ALL genetic analysis has not been used to guide therapy, it has contributed significantly to the understanding of the biology. State-of-the-art technologies in genomic and high throughput targeted sequencing are revealing novel genetic changes linked to biological and clinical features including outcome. A number of new biomarkers provide the potential for molecular targets for therapy with promise for further improvements in survival and quality of life for ALL sufferers.