The oldest mention of a place named Grduni is in a document from the Diocese of Zagreb of 1441, stating that there was an aristocrat Ivan Grdunski from the town of Grdun (near Ozalj) in Croatia. It is possible some individuals with surname Grdun moved from there to establish Grduni in Bela Krajina. With no doubt, Grduni was established by individuals with surname Grdun.
The oldest mention of an individual with surname Grdun is in the Urbarium of 1593. Residing in the župa of Preloka were Ive, Jurij, Luke, Martin and Ivan Grdun (Gardun), all likely living in Grduni.
In the oldest marriage and birth registers, there is already a Krotec family in 1765, a Pavlakovič family in 1769, a Grabrijan family in 1780, and a Rahoj family in 1787.
The Grabrijan families ended in the mid 1800s, and the Krotec family in the late 1800s.
There is only one household today inhabited residentially.
| 1800 | 1900 | 2000 | Old House # | New House # |
| Petolasovi | Petolasovi, burned in 1920, rebuilt | Preloka 1 | Balkovci 17 | |
| Jarčani | Jarčani | empty | Preloka 2 | Balkovci 16 |
| Fuziki | empty | Preloka 3 | Balkovci 18 | |
| Mikeči | Juričkovi | empty | Preloka 4 | Balkovci 13 |
| Jurasovi | Jurasovi | empty | Preloka 5 | Balkovci 12 |
| Štalarski | Štalarski | empty | Preloka 6 | Balkovci 11 |
| Grabrijanski | Grabrijanski, demolished 1904 | Preloka 7 | ||
| family Grabrijanski moved in 1904 | Grabrijanski | Preloka 8 | Balkovci 14 | |
| Mihaljevi | Mihaljevi | empty | Preloka 9 | Balkovci 15 |