|Countries South Africa|
|Date 29 April – 19 August 1988|
Champions South Western Districts
Promoted Lowveld North Western Cape South African Rugby Association South Western Districts Stellaland Winelands
The 1989 Santam Bank Trophy Division B was the fourth tier of domestic South African rugby, below the two Currie Cup divisions and Division A.
Changes between 1988 and 1989 seasons
Changes between 1989 and 1990 seasons
Regular season and title play-offs
There were six participating teams in the Santam Bank Trophy Division B. Teams played each other twice over the course of the season, once at home and once away. Teams received two points for a win and one points for a draw. The top two teams in the division – along with the top two teams from Division A qualified for the title play-off finals. The team that finished first in Division A would play at home against the team that finished second in Division B and the team that finished second in Division A would play at home against the team that finished first in Division B.
The Division B champion qualified for the promotion play-offs. That team played off against the team placed bottom in Division A over two legs. The winner over these two ties qualified for the 1990 Santam Bank Trophy Division A, while the losing team qualified for the 1990 Santam Bank Trophy Division B.
Santam Bank Trophy Finals
The top two teams from Division A and the top two teams from Division B qualified to the Trophy finals:
In the promotion play-offs, South Western Districts beat Northern Natal on aggregate and won promotion to Division A. However, due to the withdrawal of South West Africa and the Currie Cup Division B being expanded from six teams to eight teams, only nine teams were left in the Santam Bank Trophy and it was decided to merge Division A and Division B into a single division for 1990.