AbstractAbnormalities in the performance of the Indian summer monsoon (June to September) rainfall, which provides 75–90 per cent of annual rainfall, have been studied during the period 1871 to 1984 over different meteorological subdivisions into which the country has been divided. Long homogeneous monsoon rainfall series of 29 subdivisions, prepared on the basis of a constant 306 rain gauges, have been tabulated for the users in view of their great importance. The criterion adopted in identification of drought/flood over a subdivision is the percentage of rainfall departures from normal, as officially used in the India Meteorological Department.The worst drought years were 1877, 1899, 1911, 1918, 1920, 1951, 1965 and 1972 and the worst flood years were 1892, 1933, 1961 and 1983 when many subdivisions reported extremely low and excess rainfall, respectively. The probabilities of occurrence of droughts/floods are high in Haryana, Punjab, west Rajasthan, Gujarat and Saurashtra and Kutch subdivisions. The area of the country affected by drought conditions was at a maximum during the decade 1911–1920 and at a minimum during the decade 1881–1890. The decades 1971–1980 and 1921–1930 were characterized by maximum and minimum areas, respectively, under flood conditions. The percentage area of India which suffered from drought and flood was low during the continuous three decades 1921–1930, 1931–1940