The hemoglobin (Hb) content of packed red blood cell (PRBC) units is heterogenous. The efficacy of a transfusion episode can be assessed if the Hb content of the PRBC is known and the patient's post-transfusion Hb increment is also determined. This prospective study compared the efficacy of PRBC transfusion based on its Hb content versus the standard transfusion practice. A total of 160 thalassemia major patients were enrolled and randomly divided into two equal groups: Group I (n = 80) - they received ABO/RhD identical PRBCs after determining its Hb content (≥50 g); and Group II (n = 80) - they received randomly selected ABO/RhD identical PRBCs. Hb estimation and a direct antiglobulin test were performed on the post-transfusion sample (1 h). The mean Hb content of the PRBC units was significantly higher (p = 0.000) in group I (67.86 ± 8.07 g; range: 50.80-92.13 g) than group II (60.92 ± 8.29 g; range: 40.86-86.76 g). The mean Hb increment was also significantly higher in group I patients (p = 0.04). In both the groups, there was a significant negative correlation between Hb increment and weight, age, body surface area and blood volume (p < 0.05). There was a significant positive correlation between Hb increment and Hb dose adjusted for body surface area as well as blood volume (p < 0.05). PRBC transfusion was more efficacious in patients who were transfused with PRBCs having a Hb content ≥50 g as compared to those who received randomly selected PRBCs.