The research aimed at learning about the effect of profit sharing, marketing, and service quality towards the decision to use Islamic bank service of mudharabah saving in Islamic bank post acquisition issues of Bank Muamalat. The research type is quantitative descriptive with research object of Bank Muamalat of Mangkubumi Branch Office Yogyakarta. The population were 100 customers of mudharabah saving. The samples were 66 customers collected using simple random sampling technique. The data were analyzed using double linear regression technique. The result of the research indicated that profit sharing, marketing, and service quality affected positively and significantly towards the decision to use Islamic bank service of mudharabah saving as much as 54,5% determinan koefisien.