The championships took place in Raheny on Sunday.
A clutch of silver medals are coming back to Offaly after the National Relay Championships in Dublin last weekend.
Tullamore Harriers landed second place thanks to sisters Danielle and Nadine Donegan, along with Niamh O'Connor on Sunday.
The format saw the first leg over the distance of a mile, followed by two miles for the second leg, and a mile again for the third leg.
Dundrum South Dublin Ac took gold in 20.38, the Tullamore women followed in 20.43, with UCD just behind in 20.45.
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