Objective: To analyze the positive predictive value (PPV) and negative predictive value (NPV) of upper lip bite test (ULBT), ratio of patient\'s height to thyromental distance (RHTMD), and Mallampati classification (MPC) anticipating difficult intubation. Materials and methods: Adults undergoing elective intubation procedures under general anesthesia were graded using MPC, ULBT, and RHTMD in this prospective study. Cormack and Lehane (CL) were compared to three approaches. Grades III and IV are believed to be the most challenging to intubate. Calculations were made to determine each method\'s sensitivity, specificity, PPV, and NPV, as well as accuracy. Results: Out of 60 patients, 18 (30%), 21 (35%), and 21 (35%) were from CL grade I, grade II, and grade III, respectively. ULBT was found to be the least useful test to predict difficult intubation with 0% sensitivity. MPC and RHTMD had a sensitivity of 61.9% and 95.2%, respectively. Conclusion: In assessing and preparing for anticipating a problematic endotracheal intubation airway, RHTMD as a single preoperative bedside test offers a high level of accuracy when compared to MPC and ULBT.