A pharmaceutical solid oral aripiprazole preparation is provided which has a) at least one dissolution rate measured after storage in the open at 25°C/60% RH for six months selected from the group consisting of 70 % or more at pH 4.5 after 60 minutes, and 55 % or more at pH 5.0 after 60 minutes; or b) at least one dissolution rate measured after storage in the open at 40°C/75% RH for 1 week selected from the group consisting of 70 % or more at pH 4.5 after 60 minutes, and 55 % or more at pH 5.0 after 60 minutes.