The vaccination planning tool for avian influenza supports evidence-based planning and preparedness for vaccinating poultry at national and regional levels. This study describes the development, testing, and application of a vaccination planning tool for H5N1 highly pathogenic avian influenza (HPAI) used in two South Asian countries. The tool consists of eight planning clusters, 37 planning elements, and 303 referenced planning criteria. Both countries attained a score of 52% among planning clusters as a measure of preparedness. The highest and lowest planning cluster scores included vaccination strategies and financial readiness, respectively. The comprehensive vaccination program was identified as the most-useful planning cluster for assessing preparedness, and 86% of participants indicated that the objectives of the planning tool were achieved. Based on these results, the planning tool provides a structured approach for decision makers to develop their national vaccination program for HPAI as part of an overall strategy for the progressive reduction and control of endemic influenza viruses in poultry.