The Mexican Social Security Institute (IMSS) belongs to the Mexican health sector and provide health servicesto beneficiaries, employers, pensioners and retirees across Mexico. However, there are evidences thatbeneficiaries are not satisfied with the health services they receive. For this reason, with a sample of 417 out of669 workers of the General Hospital number 1, located in the State of Colima, Mexico, was conducted thisresearch to measure the level of satisfaction of IMSS workers, the factors underlying this satisfaction and topropose an instrument to measure job satisfaction in this Mexican institution with the purpose to generateefficient management models for workers that can help to improve the client satisfaction levels. UsingConfirmatory Factor Analysis (CFA) was confirmed an instrument of 21 items and five factors (personaldevelopment, interpersonal relationship, recognition, work nature, and work environments) to measure jobsatisfaction in a Mexican hospital and also we shown evidence that the same construct is appropriate for bothgenders with the exception that female presented higher levels of satisfaction in their job for the personaldevelopment.