Background and aim: The effectiveness of any vaccine depends on maintaining it at recommended temperatures from manufacture to administration. Health workers in any health facility play an important and vital role in maintaining the cold chain and vaccine efficiency. Therefore, the aim of conducting this research was to evaluate the practice of health workers working in the Expanded Program on Immunization in Sa’adah, Yemen in the correct procedures to maintain the effectiveness of the vaccine and recording data. Method: This study was conducted on 60 health facility (H.F) in 11 districts in Sa’adah Governorate, Yemen during the period from 1 June to 30 July 2019. The focus was on the checklist used to assess the general practices of healthcare personnel participating in the immunization program. The location of the refrigerator, the arrangement of the vaccines, the presence of a thermometer, the handling of the syringes, the cleaning of the injection area, the direction of the pentavalent and measles vaccination needle, and the method of storing the vaccines during the sessions were evaluated. Data were entered and cleaned using Microsoft Excel 2019 and exported to SPSS version 26. Results: The findings show that, the ages of participants ranged from 23-55 years with Mean±SD (34.17±7.310) and 38 (63.3) were male. From a total of health facilities, 43 (91.5) had a good site of refrigerators, 45 (95.7) had a good distance from the wall, and 42 (89.4) had thermometers. There is no significant correlation between the socio-demographics of HCPs and score practice, the total practice scores for HCPs were (21.7%, and 78.3%) for right practice and right but not complete practice, respectively. Conclusion: Only a small percentage of healthcare providers have corrected practice, while a large number have shown correct but not perfect practice. Hence, regular supportive supervision, ongoing technical support, and on-the-job training are highly recommended to improve the healthcare provider's practice with regard to immunization. Peer Review History: Received: 2 January 2023; Revised: 11 February; Accepted: 6 March 2023, Available online: 15 March 2023 Academic Editor: Dr. Ali Abdullah Al-yahawi, Al-Razi university, Department of Pharmacy, Yemen, alyahawipharm@yahoo.com Received file: Reviewer's Comments: Average Peer review marks at initial stage: 6.0/10 Average Peer review marks at publication stage: 7.0/10 Reviewers: Prof. Hassan A.H. Al-Shamahy, Sana'a University, Yemen, shmahe@yemen.net.ye Dr. Bilge Ahsen KARA, Ankara Gazi Mustafa Kemal Hospital, Turkey, ahsndkyc@gmail.com Dr. Amany Mohamed Alboghdadly, Princess Nourah bint abdulrahman university, Riyadh, amalbgadley@pnu.edu.sa Similar Articles: UTILIZATION OF HEALTH MANAGEMENT INFORMATION SYSTEM AND ASSOCIATED FACTORS IN HEALTH INSTITUTIONS OF KEMBATA TEMBARO ZONE, SOUTHERN ETHIOPIA INVESTIGATING THE OBSTACLES OF IMPLEMENTING HEALTH INFORMATION SYSTEMS FROM VIEWPOINT OF PERSONNEL OF MEHRIZ HEALTHCARE SYSTEM IN 2017 DETERMINING THE IMPACT RATE OF TRIAGE TRAINING ON AWARENESS AND SKILL LEVEL OF PRE-HOSPITAL EMERGENCY PERSONNEL OF FASA CITY