Microarray images contain a large volume of genetic data in the form of thousands of spots that need to be extracted and analyzed using digital image processing. Automatic extraction, gridding, is therefore necessary to save time, to remove user-dependent variations, and, hence, to obtain repeatable results. In this research paper, an algorithm that involves four steps is proposed to efficiently grid microarray images. A set of real and synthetic microarray images of different sizes and degrees of rotations is used to assess the proposed algorithm, and its efficiency is compared with the efficiencies of other methods from the literature.