Chelonians have a unique anatomy that causes problems when it comes to using common techniques for assessing health status and diagnosing disease; for example, palpation, auscultation, radiography and exploratory laparotomy. As a result, blood analysis has been reported to be a valuable and non-invasive diagnostic tool for assessing the health status of wild and captive tortoises and turtles. However, chelonian haematology is not as advanced as it is for mammals or birds, and there is great variability and subjectivity when obtaining and assessing blood results. This article, the first in a two-part series, reviews and discusses the collection and handling of blood samples in turtles and tortoises. The second article, to be published in a subsequent issue of In Practice, will describe the different blood cells found in turtles and tortoises, and discuss the main problems encountered with identification.