Aim: This study aimed to determine the agreement between arterial blood gas (ABG) and venous blood gas (VBG) analyses in a pathologically diverse patient population who presented to the emergency department. Materials and Methods: This cross-sectional study was conducted in the emergency department of a tertiary care hospital during the period from February 2019 to June 2020. A total of 113 patients presenting with various medical conditions confirmed on ABG by a physician were recruited. Both arterial and venous blood samples were collected for blood gas analysis. Using a Bland-Altman plot, data obtained were analyzed for agreement. IBM SPSS version 22 was used for the data analysis. Results: Among the 113 study participants, the arterial and venous pH values, base excess, and bicarbonate level show acceptably narrow 95% limits of agreement in the Bland-Altman plot (-0.06 to 0.08, -4.08 to 2.30, and -2.59 to 0.89, respectively). Agreement in partial pressure of oxygen and oxygen saturation measurements was poor (95% limits of agreement, -8.38 to 101.06 and 0.35 to 0.58, respectively). Agreement of partial pressure of carbon dioxide shows an acceptably narrow agreement (95% limits of agreement, -10.61 to -2.18). Conclusion: VBG analysis for pH, bicarbonate, and base excess may be a reliable substitute for ABG analysis in the initial evaluation of adult patients presenting to the emergency department.