The East Zone of the Ranji Trophy, 1990-91, the premium domestic cricket tournament in India saw the participation of 5 teams, all the regular ones. The teams were representing five different states form the Eastern region of India, in the tournament and they included the likes of Bengal, Assam, Tripura, Bihar and Orissa. All the teams tried their best to claim the top spot in the zone, by beating the other teams and securing a birth in the knock out level was also their another principal objective. However, only the teams like Bengal and Bihar could eventually do so from the zone, as they earned total of 79 and 65 points, respectively, at the end of the zonal level league matches. They went on to the knock out level of the tournament for playing against the top teams of the other zones, for the championship title.

The Tripura and Orissa teams played against each other in the first East Zone league match of the Ranji Trophy, 1990-91 and the match was held at Agartala from 23-26 November, 1990. The Orissa team got a very good start in the tournament, as it won the match with a very good margin of an innings and 197 runs and earned 23 points from it. The Tripura team also earned 2 points from the match. The teams of Assam and Bihar played against each other in the second match of the zone and the match was held at Guwahati from 23-26 November, 1990. The match remained drawn during the specified period of time and the match officials awarded the Assam and Bihar teams 14 and 8 points, respectively for the match. The Assam team played in the third match of the zone also and this time, it played against the Orissa team at Guwahati from 30 November-03 December, 1990. The Assam and Orissa teams earned 11 and 9 points from the match, as it remained drawn during the stipulated duration.

The match between the teams of Bengal and Bihar was also held during the same timing from 30 November-03 December, 1990 and the two teams played the match at Calcutta. The match went on to be a drawn one during the specified period of time and the Bengal and Bihar teams earned 18 and 10 points, respectively from the match. The Bengal team played against the Orissa team in the fifth of the East Zone league matches in the Ranji Trophy, 1990-91 that was held at Calcutta from 06-09 December, 1990. The Bengal team played very well in the match and clinched a victory of an innings and 76 runs for earning 22 points from it. The Orissa team also earned 4 points from the match. The Assam and Tripura teams then played against each other in the next match of the zone and the match took place at Agartala from 07-10 December, 1990. The Assam team earned 21 points from the match, by clinching a victory of 363 runs and the Tripura team earned 6 points from the match, as well.

The seventh of the East Zone league matches in the Ranji Trophy, 1990-91 saw the Bihar and Orissa teams playing against each other at Ranchi from 24-27 December, 1990. The drawn match saw the Bihar team earning 13 points and Orissa earning 6 points from it. The Assam and Bengal teams then played against each other in the next match of the zone, which was held at Guwahati from 25-28 December, 1990. The match was a drawn one and the Bengal and Assam teams earned 14 and 9 points, respectively from the match.

The teams of Bihar and Tripura were involved in the next match of the East Zone and the two teams played the match at Jamshedpur from 30 December, 1990 - 02 January, 1991. The Bihar team won the match by a very good margin of an innings and 231 runs to earn 25 points and the Tripura team also earned 2 points from the match. The last of the East Zone league matches in the Ranji Trophy, 1990-91 was played between the teams of Bengal and Tripura and the match was held at Calcutta from 06-09 January, 1991. The match saw the Bengal team winning by a wonderful margin of an innings and 2556 runs and also earning 25 points from it. The Tripura team earned 6 points from the match as well.