Acquisition is believed as a strategy to improve performance of a company. However, several previous researches shows that acquisition can not improve the performance. The purpose of this study is to examine the impact of acquisition on acquirer companies’ financial performance. The population of this study is 21 Indonesian companies that involved in acquisition during 2011-2013. The data is financial ratios, collected from Indonesian Capital Market Directory provided by Indonesian Stock Exchange website. To analyse the performance, five ratios are used in this research. Paired sample t-test is applied on the ratios with the help of statistical software called PASW (Predictice Analytics Software). The findings confirm that liquidity, leverage, efficiency, profitability, and market value decrease insignificantly a year after acquisition. Therefore, it is concluded that there is no different in financial performance before and after acquisition. Keywords: Acquisition, acquirer companies, financial performance, financial ratios