Background: This study aimed to evaluate Sacroiliitis on MRI in clinically Suspected Cases of Ankylosing Spondylitis. Material and methods: It was a hospital-based, cross-sectional, comparative, descriptive, prospective study that included 50 subjects. Patients who were clinically suspected of having symptoms related to sacroiliitis had been included in the study. Those who had tumour or tumour-like conditions, congenital spinal anomalies, and those who had absolute contraindications to MRI were excluded from the study. Siemens 1.5 Tesla MRI system “Magnetom Essenza” with Tim + Dot technology machine was used for the study. All the collected data were entered in Microsoft Excel Sheet and then transferred to EPIINFO. software for analysis. Quantitative data were presented as frequency and Percentages. Results: On MRI, most common finding was mild Articular irregularity 36% whereas 28% had moderate articular irregularity and 2% had severe articular irregularity, while 34% did not show any findings on MR imaging. Joint Space Narrowing among study subjects by using MR Imaging was done. On MR imaging most common observation was 38% did not show any Joint Space Narrowing, followed by 34% had mild Joint Space Narrowing, 26% had moderate Joint Space Narrowing, and one patient presented with severe Joint Space Narrowing. All the study subjects were examined for bony erosion which is suggestive of inflammatory changes. On MR imaging most common finding was mild erosions 36% whereas 28% had moderate level erosions and one patient presented with severe erosion while 34% did not show any findings on MR imaging. Conclusion: Ankylosing Spondylitis is a common problem in the growing population, affecting patients with a gap of 5-8 years between the onset of symptoms & establishment of diagnosis using conventional radiography. In this study, MRI detected more cases of AS as compared to X– ray that too on an earlier stage of disease. Keywords: MRI, Ankylosing Spondylitis, Sacroiliitis.