The negotiations centre around a proposed one-year loan deal for the 25-year-old South African with a view to a permanent move to Goodison Park at the end of the season.
"Everton have contacted us and we are currently talking to the English club," said Dortmund director of sport Michael Zorc to local newspaper, Ruhr Nachrichten.
Pienaar only joined Borussia last summer when Tomas Rosicky moved to Arsenal, but he struggled to fill the boots of the Czech midfielder and failed to find the back of the net in 25 Bundesliga appearances.
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