Words including "Jude Raus" - German for "Jew Out" - and "Hitler Good," in English, were found in red paint Saturday at the former Plaszow camp near Krakow.
In addition, a swastika was spray-painted on the monument.
'Hitler good' (Photo: Reuters)
The vandalism was discovered a day before a planned memorial march marking the 67th anniversary of the liquidation of Krakow's ghetto.
On March 13, 1943, German soldiers started a two-day action in which they emptied Krakow's ghetto of its estimated 16,000 Jewish residents, shipping them to Plaszow and to the Auschwitz-Birkenau death camp.
The news agency PAP quoted a police official, Anna Zbroja, as saying authorities are on the spot trying to determine when the vandalism occurred.