We propose the realization of the Aharonov-Casher (AC) effect in a mesoscopic semiconductor ring. We find that the thermodynamic characteristics of the excitonic gas in the semiconductor ring are periodic in the AC flux F through it with a period F 0 = hc/2 μ B g, where μ B is the Bohr magneton and g is the g-factor. The amplitude of oscillations passes through a maximum at the temperature T∼Δ (Δ is the typical energy of excitons). Outside this region it decreases either exponentially (if T ⪡ Δ), or according to a power law (if T ≳ Δ).