Objectives: The present study was to evaluate the complications occurring during and after intubation in relation to the predictive assessment of difficult intubation in Heaven Criteria versus Modified Lemon Criteria. Methods: All patients were evaluated for difficult intubation using both HEAVEN criteria and Modified LEMON criteria before performing the procedure. Intubation was performed following the standard rapid-sequence or delayed-sequence protocol. Vitals including heart rate, blood pressure, oxygen saturation (SpO₂), and respiratory rate were recorded pre- and post-intubation. Peri-intubation and post intubation complications, such as: Hypoxia (SpO₂ < 93%), multiple attempts at intubation (> or = 2) and hemodynamic instability (SBP < or = 90 or use of Vasopressor agents) were recorded. Results: A total of 200 patients were enrolled for intubation. The gender distribution showed a male predominance, with 122 males (61%) and 78 females (39%). The mean age of participants was 55 years, with a range from 18 to 86 years. Most common comorbidity was hypertension followed by diabetes mellitus and Cardiac condition. Mean Intubation time for successful 1^st attempt was 23.57± 8.34 but it increases significantly (p<0.001) by 118.57% with multiple attempts. The slope of the graph of successful intubation is higher for HEAVEN score (0.0294) as compared to Modified LEMON score (0.0206). Out of total 200 patients, 60 developed post intubation hypotension (SBP < 90 mmHg or requiring vasopressor support) and 4 developed post intubation hypoxia (SpO2<93%). Conclusions: Hypoxia and hypotension were the most common post intubation complications. The number of attempts was directly proportional to the incidence of complications such as hypoxemia, bradycardia and aspiration associated with hypotension during intubation. HEAVEN criteria scores significantly increased the number of attempts for successful intubation as compared to modified Lemon criteria.