The 30-share index fell by 209.74 points or 0.82 per cent to 25,396.88 with sectoral indices led by power, realty, banking, IT, technology, auto and capital goods in deep red.
The gauge had gained a marginal 3.52 points on Friday.
On similar lines, the National Stock Exchange index Nifty slipped below the 7,800-mark by falling 56.70 points or 0.72 per cent to 7,793.10.
Brokers said sentiment dampened here following a 3.62 per cent plunge in Tokyo equities, as a sharp rise in yen hit exporters, leading to a sell-off across Asia in holiday- thinned trade and on global economy worries-fuelled sharp losses in Wall Street and Europe on Friday.
Meanwhile, markets in China, Hong Kong, Malaysia and Singapore were closed today for public holidays.