It seems that profit warnings convey less certain signals compared to earnings announcements, because market participants may anticipate the lowering of a firm’s targets from other news about this firm, about the industry in which this firm operates, or about the general economy. This is probably one of the reasons why there is very little research focused on profit warnings. In this paper, we examine the information content of profit warning announcements which have taken place on the Warsaw Stock Exchange over the last decade. It turns out that profit warnings are accompanied by a statistically significant stock price reaction on the day after the announcement is released. There is no reason to believe that price adjustment starts before a profit warning, at least in a three-day-horizon. In addition, a cross-sectional regression analysis is used to determine whether the market response is dependent on other factors, such as e. g. firm size.