To correlate the pre-operative Temporal Bone High Resolution Computer Tomography (HRCT) Scan findings with intraoperative findings in Chronic Otitis Media-Squamous type. This prospective, correlative, observational study was done at Department of Otorhinolaryngology and Head and Neck Surgery, Tribhuvan University Teaching Hospital, Kathmandu. 156 patients underwent mastoid surgery under General Anaesthesia from October 2017 to November 2018. Ethical committee approval taken from the institutional review committee. Informed consent regarding the study was taken prior to surgery. The peroperative findings were correlated with preoperative HRCT findings. Cohen's kappa coefficient (-value) was used to estimate the degree of correlation. Statistical analysis was done using SPSS version 25. Total 156 patients between 8 and 70 years of age were enrolled in the study. Presence of cholesteatoma/granulation on HRCT scan was found with 100% sensitivity with k-value of 0.569 denoting fair agreement. Regarding ossicular status, malleus showed maximum k-value of 0.525 with sensitivity of 81.3% followed by stapes and incus with k-value of 0.308 and 0.380 and sensitivity of 68.3% and 70.2% respectively. Sinus plate status showed perfect radiosurgical agreement with k-value of 1.0 and sensitivity and specificity of 100%. Bony facial canal demonstrated slight agreement with k-value of 0.506 and sensitivity of 45.8%. Dural plate status showed fair agreement with k-value of 0.503 and sensitivity of 38.9%. For Lateral Semicircular Canal (LSCC) erosion, we found very good agreement with k-value of 0.893 with sensitivity of 90.9%. Preoperative HRCT scan temporal bone correlates well for the detection of disease presence and shows good radiosurgical agreement for sinus plate erosion, LSCC erosion but fair agreement for dural plate erosion and malleus erosion. Plain HRCT scan with 3-D reconstruction is a poor predictor of bony facial canal, incus and stapes erosion.