1988.  Fridtjof Nansen (1861-1930), Norwegian explorer of the North Pole and arctic areas.  
The stamp was issued in commemoration of the 100th anniversary of Nansen's first Greenland Expedition.  

1988.  Passenger Steamer on the Harbour in 1910.

1988.  The Railway Station in Monaco in 1910. 

1989.  Ship in the Harbour.

1989.  Casino, La Salle de Jeux.

1989-1991.  Definitive series, depicting Prince Rainier III.  Fifteen stamps.  See also Scott # 1790-1799. 

1989.  25th anniversary of the Princess Grace Foundation.  Princess Grace of Monaco, and her daughter Princess Caroline.

1989.  40th anniversary of the reign of Prince Rainier III. 40th anniversary of government of Prince Rainier III.  Please note that a similar bloc of the same design was issued in 1999 (blue colour) at the occasion of Prince Rainier IIIs 50th government anniversary (Scott # 2128).  

1990.  Pierrot Ecrivain.

1991.  Portrait of the French painter Claude Monet, by the French painter Auguste Renoir.

1992.  Mercantour National Park.  Bird of Prey "Gypaetus Barbatus".