The paper describes an investigation which is being conducted by a life office into the mortality experienced by certain classes of impaired lives. The investigation was initiated in 1947 and the results for the period 1947-1958 are compared with a control experience of first-class lives.

It is emphasised that owing to the limited amount of data, and also to a certain lack of strict comparability in the control experience, the results must be regarded with some caution. The purpose of the paper is, in fact, not so much to communicate statistical information as to describe the methods followed in planning the investigation and to promote a discussion of the feasibility of setting up an investigation under the auspices of the Joint Mortality Investigation Committee to which all life offices operating in Great Britain would be invited to contribute data.

The paper presents a coding system for the impairments covered and discusses briefly the results so far obtained within the main groups. For some of the larger groups it has been possible to include a summary analysis by cause of death.