The efficacy of the intratympanic administration of CMC steroid for the treatment of inner ear disorders was investigated in 64 guinea pigs. Dye solution without CMC injected into the middle ear was cleared through the eustachian tube on the first day. When dye plus CMG were injected, they remained in the middle ear in 100% of the guinea pigs on the first day, in 67% on the fourth day and in 33% on the seventh day. The uptake of steroid in the perilymph after the intratympanic administration of CMC steroid was significantly higher than after the intratympanic administration of steroid without CMC on the fourth and seventh days. These results indicate that CMC delays the clearance of steroid from the middle ear and enhances the uptake of steroid in the inner ear through the round window.