This research aims at testing and confirming existence of selected behavioral biases of investors that affect their decisions. Five behavioral biases affecting irrational behavior of investors were selected: overconfidence bias, illusion of control bias, confirmation bias and recency bias and optimism bias. Primary data was collected through a questionnaire from 300 investors from banks, insurance companies, stock exchanges etc. The results were obtained by employing a correlation and regression analysis for the presence of behavioral biases and to detect degrees of their influence on decision making. Correlation results indicate moderate association between behavioral biases and decisions of investors. Outcome of the research indicates that while making financial decisions investors are moderately affected by behavioral biases.