In this paper we investigate if directors of Australian companies earn persistent profits on their reported trades, if these abnormal profits are significant enough to be mimicked by outsiders, and if these insider trades have an effect on returns of other investors. We find that insiders take advantage of their private information in stocks of larger corporations, but generally do not in medium and small capitalization firms, indicating that they insiders are attracted to the liquidity and a greater presence of uninformed traders in large stocks. Insiders appear able to determine the value of their information in by trading larger volume and larger portion of their holdings when they have access to valuable information. We find that outsiders can make profitable trades by following insider's trades in large firms, but abnormal returns mimicking insiders in small and medium size firms are limited to insiders' sell trades only, and otherwise result in losses for outsiders. Implications on market fairness and integrity are discussed and conclude that market quality can be improved with public access to good quality aggregated data on reported director insider trades.