The distribution of Na⁺, K⁺-ATPase, Na⁺, K⁺-ATPase α₁, Na⁺, K⁺-ATPase β₂, Na⁺, K⁺-ATPase Nor 20β₂, carbonic anhydrase(CA), and aldehyde dehydrogenase(ALDH) were investigated immunohistochemically in paraffin sections of rat inner ear. The basolateral plasma membrane of marginal cells in the strial vascularis was positive for Na⁺, K⁺-ATPase β₂ and Na⁺K⁺-ATPase α₁ antisera. The type I fibrocytes of the spiral ligament, located under the stria vascularis, stained for Na⁺K⁺-ATPase Nor 20β₂ and CA antisera. Type II fibrocytes under the outer sulcus and spiral prominence epithelium were found to contain Na⁺, K⁺-ATPase, Na⁺, K⁺-ATPase α₁ and CA. Type III fibrocytes lying adjacent to bone in the inferior region of the superficially in the inferior part of the spiral ligament contained Na⁺, K⁺-ATPase, Na⁺, K⁺-ATPase Nor 20β₂, CA and ALDH. The cells in the supralimbal and suprastrial region contained Na⁺, K⁺-ATPase. These findings demonstrate functional diversity of fibrocytes of the inner ear providing a basis for classifying those in the spiral ligament and suggest some important roles of fibrocytes in spiral ligament on the inner ear fluid and ion transport system.