The influence of gravity on the microstructure of unidirectionally solidified Cu-Pb monotectic, Ag-Si and Fe-C eutectic alloys is studied. In order to examine the influence of gravity in a 1 g environment, both the upward (opposite to direction of gravity) and downward (direction of gravity) unidirectional solidifications are carried out. The results are as follows: (1) For the upward solidified Ag-Si eutectic alloy, the eutectic Si continuously grows. On the other hand, in the downward solidified Ag-Si alloy, the Si grows discontinuously and disperses into the α-Ag matrix. (2) No morphological difference in the eutectic growth is observed between the upward and downward solidified Fe-C eutectic alloys. (3) In the case of the upward solidified Cu-Pb monotectic alloy, a banded structure, which consists of Pb-rich layers and Cu-rich layers, is observed. However, such a banded structure is not observed in the downward specimen. (4) The banded structure is not found in the upward solidified Cu-Pb-0.05 mass%Al and Cu-Pb-0.1 mass%al alloys. In the Cu-Pb-0.05 mass%Al alloy, a fibrous L2 phase grows continuously parallel to the growth direction at low growth rate. Only 500 mass ppm addition of aluminum induces the morphological change of the monotectic L2 phase.