The effect of the Coriolis acceleration on natural convection is presented in this chapter. When the imposed thermal gradient is perpendicular to the direction of the centrifugal body force unconditional natural convection occurs. Then the Coriolis effect is reflected in creation of secondary flows in a cross section perpendicular to the direction of the main convection. When the natural convection occurs due to gravitational buoyancy and the thermal gradient is parallel to the direction of the gravity body force natural convection occurs conditionally. Stability analysis is then required and presented for stationary or possibly oscillatory convection. Weak nonlinear solutions identify then the direction of the bifurcations for different values of the controlling parameters.