Introduction: Manual handling tasks are considered to be the main causes of occupational back pains. Therefore, the assessment of manual handling tasks for the prevention of work musculoskeletal disorders (WMSDs) sounds necessary. The aim of this study was to assess the manual handling tasks using the key item method (Kim) and determine its relationship with the prevalence of musculoskeletal disorders using CMDQ tool in the workplace of the central workshop in Abadan oil refinery.
 
Materials & Methods: This cross-sectional descriptive-analytical study was performed on 103 employees of Abadan's central workshop, using the simple sampling. Data were collected using KIM and CMDQ questionnaires and analyzed using Pearson and multiple linear regression tests in SPSS version 20.
 
Findings: Based on the results of the assessment by KIM method, 48 subjects were in the risk level 1, 36 subjects in the risk level 2 and 19 subjects in the risk level 4. Also, based on the score of CMDQ questionnaire, 95 people were with very minor and negligible disorders, 4 cases with minor disorders, 1 person  with very low disorders, 1 person with low disorders, one with medium disorders, and one  with high disorders. In addition, the results of statistical tests showed  a significant relationship between scores of KIM and WMSDs (P = 0.002). However, there were no significant relationship between these two variables and demographic characteristics of individuals.
 
Discussion & Conclusions: Our investigation demonstrated that manual handling tasks and other tasks related to it have a direct relationship with the incidence of WMSDs; so that, the increase in the workload and nature of the manual handling tasks will enhance the severity of WMSDs. In order to reduce the severity of such disorders, corrective measures such as training programs, posture modifications, and job designs seem necessary.