Bubbles and slugs rising in vertical pipes of good and poor wettability were observed with a high-speed video camera in normal gravity as well as in microgravity. The wettability of the pipe did not affect the mean rising velocity of bubbles in microgravity. The same was true for the mean rising velocity of slugs in microgravity. An empirical relation was derived for the mean rising velocity of bubbles and slugs in mirogravity as a function of the superficial velocities of gas and liquid.