Mahindra & Mahindra (M&M) had sold 43,460 units in the same month last year, the company said in a statement.
M&M's domestic sales stood at 35,499 units last month as against 42,104 a year earlier, down 15.68%.
Sales of passenger vehicles, including Scorpio, XUV 5OO, Xylo, Bolero and Verito, stood at 18,085 units compared with 22,244 units in May 2013, down 18.69%.
Four-wheel commercial vehicle sales declined 13.55% to 12,836 units as against 14,848 units, it said.
Exports rose 74.77% to 2,370 units from 1,356 units earlier.
"Auto sales continue to remain subdued for many players, at the back of yet another challenging month for the industry," M&M Chief Executive (Automotive Division) Pravin Shah said.
He said: "Post the electoral mandate, we expect to see improved sentiment resulting in a better economic situation which we hope will lead to a gradual increase in demand.