This study aimed to examine the relationship between CEO narcissism (measured CEO signature size) and both firm performance (measured by the return on assets ratio) and firm value (measured by Tobin's Q). And by resorting to a sample of 80 companies from various sectors of the Egyptian stock market, spanning from 2017 to 2019, with a total of 240 observations. The study proposed two hypotheses: 1) There is a negative relationship between the CEO's narcissism and the firm's performance; 2) There is a negative relationship between the CEO's narcissism and firm’s value. Both hypotheses were rejected. While regarding the first hypothesis, results indicated that there is a positive significant relationship. As for the second hypothesis, the relationship was not significant. This means that investors overlook the CEO's narcissism in their decision-making models.