Paintings by Gauguin, Cezanne and Van Gogh are being displayed in Cardiff for the first time, thanks to a swap with the National Gallery of Scotland.
Midday by Cezanne is one of the works on show in Cardiff
The exchange also sees some of the best works from the National Museums and Galleries of Wales exhibited in Edinburgh.
All the works in both shows came from two pairs of prolific patrons.
In Scotland, it was Alexander and Rosalind Maitland, and in Wales, it was sisters Gwendoline and Margaret Davies.
Both bequested their collections to their national galleries on their death, and this new exchange highlights the similarities and differences between the pictures they amassed.
Rain by Van Gogh was gifted to the National Gallery of Scotland
Ann Sumner, Senior Curator (Fine Art) at the National Museum and Galleries of Wales said the Cardiff exhibition, which opened its doors on Saturday, was "amazing".
"There are 12 Impressionist paintings in the exhibition - five loaned from Scotland," she said.
"We have one of the most famous of the Gauguins - Three Tahititians - in the world here, and a wonderful Van Gogh"
"It is very exciting - we have wanted to work with Scotland for some time - we are both doing new and exciting research."
She said it was also an opportunity to highlight the Welsh collection in Scotland and hoped it might pave the way for more exchanges in the future.
Three Tahitians is lauded as one of Gauguin's best works
"That is just what we very much hope. There are many parallels between our collections we could explore in the future."
Frances Fowle, curator of the National Gallery of Scotland, said: "This is a wonderful opportunity to showcase major Impressionist works from the Cardiff collection.
"The importance of the Davies sisters as pioneer collectors cannot be underestimated and we hope this marks the beginning of an ongoing relationship with our colleagues in Wales."
The exhibitions at the National Museum and Gallery in Cardiff and the National Gallery in Edinburgh will both run until 26 June.