Microarray technology has increased exponentially in the past few years. Such technology encompasses various applications related to drug design, tumor detection, clinical diagnosis and treatment, and environmental health research. However, the segmentation of the spots in microarray image is still a problem due to variations of spots qualities such as spots shapes and sizes for example. Hence, we have introduced a new microarray spot segmentation algorithm based on Integro-Differential Operator (IDO). Because it includes a spot detection step, this IDO can be used to find any spot regardless of its size and shape within the microarray image. The IDO algorithm is applied on the cDNA microarray images to improve the accuracy and the efficiency of the spots segmentation process. As the IDO is able to segment each spot based on the fact that the illumination difference between the inside and the outside of …