Police in County Tyrone have seized 1.7kg of mephedrone with an estimated street value of £51,000.
Two men were arrested following the discovery during a house search near Coalisland.
Inspector Gerry McGrath said the "significant" seizure had "taken dangerous drugs off the streets of Cookstown and Dungannon".
In April 2010, mephedrone was banned and reclassified as an illegal Group B drug under the Misuse of Drugs Act.
Prior to that mephedrone was sold in shops as plant food and was seen as a way to get a legal high.