The operation for otosclerosis consists essentially of two stages: Stage one is the approach to the labyrinth; stage two is the actual fenestration of the labyrinth. The newest and most important strides in the success of the operation have been made in stage two, the most important stage, preventing the osteogenetic closure of the nova ovalis. Selection and accurate diagnosis of patients is very important. Results have improved considerably with the employment of a new technique as shown by Shambaugh and his co-workers at the Northwestern University, Chicago, claiming up to 89 per cent. success.