The morphologic findings on a peripheral blood smear can provide important clues that help establish a diagnosis or guide the workup of many clinical disorders. Finding a blast - whether clinically expected or not - is one of the most impactful of such findings. Pathologists, clinical haematologists, technologists, and trainees in the medical field often feel the need to refer to an illustrated reference when encountering suspected blasts and blast-mimics. This article provides a practical concise resource that demonstrates the morphological features of the various types of blasts and illustrates the cytologic characteristics that help distinguish them from their benign mimickers in the paediatric population.