Between 1801 and 1921 Ireland in common with the rest of the British Isles was represented in the house of commons at Westminster. During this time the basis of the Irish representation underwent considerable change both in relation to the number of Irish M.P.s, electors and population and in comparison with the number of M.P.s, electors and population for Great Britain. The purpose of this article ir, by means of statistical tables, to analyse the Irish electorate between 1868 and 1915 and in particular to show the effect of the electoral reforms of 1868 and 1884–5. The electorate of Ireland will be viewed not only in the context of the separate Irish constituencies and the proportion of electors to adult males and population in each but also in the context of the whole of the British Isles and the total number of electors and population with the proportion of electors to population in each country. As well the average number of electors and population per M.P. for the different countries will be shown.