There are many oil companies operating in Macaé-RJ, Campos basin, they value the safety of work and the lives of its employees. These companies do a study to verify the health status of their employees' spine and result in a database with six attributes, such as: Pelvic incidence, Pelvic inclination, Lumbar lordosis angle, Sacral inclination, Pelvic radius and Degree of Spondylolisthesis. For in Brazil, recently, Social Security has released statistical studies that show back pain as leaders in the ranking of departures in the first half of 2016, a fact that directly affects the productivity of companies and health of their employees. This article aims to apply the KDD process, specifically the task of Data Mining classification, ie, classify if the employee will be fit or unfit for the job. The decision tree was the technique chosen through the algorithm J48 to verify the possibilities of treatment of the collaborators in the prevention and improvement in the working environment, and even, a change in the management was made from the results found. It resulted in inadequate staff postures, inadequate service stations, lack of training in equipment handling, lack of knowledge about cargo handling.