The 30-share index, which had gained 174.60 points in the previous three sessions, fell back by 140.52 points, or 0.71 per cent, to 19,502.23, with metal, consumer durable, realty, power and auto sector stocks coming under pressure.
In a similar fashion, the wide-based National Stock Exchange index Nifty shed 37.15 points, or 0.62 per cent, to 5,905.90.
Brokers said besides profit-booking by participants after three sessions of gains, a weak trend on the Asian bourses led to the fall in Sensex.
In the Asian region, Japan's Nikkei Index was down 0.80 per cent, while Hong Kong's Hang Seng index shed 1.62 per cent in early trade.
The US Dow Jones Industrial Average ended 0.77 per cent lower yesterday.