Two offenders, including one armed with a knife, entered the Willowbank Dairy, in George St, just after 1am.
Detective Sergeant Chris Henderson said the offenders handed over a note, demanding property, and the pair made off with a ''large amount of cash and a large quantity of synthetic cannabis''.
The synthetic cannabis was of different varieties and worth hundreds of dollars.
''Anyone who comes across anyone offering for sale synthetic cannabis, should contact police,'' Det Sgt Henderson said.
The pair, who wore black clothes, had their faces covered during the robbery.
The two shop assistants were shaken but unhurt.
Det Sgt Chris Henderson urged anyone with information about the robbery to contact Dunedin police on 471-4800, or provide information anonymously via the Crimestoppers line, 0800 555 111.
• Would-be thieves smashed a window in a failed attempt to snatch a bike frame from a central Dunedin cycle shop early yesterday.
A window at Cycle World, in lower Stuart St, was smashed about 2.20am and an attempt made to steal an alloy bike frame.
The alleged offender was last seen running down the one-way system.
• A 20-year-old man spent the night in police custody after he allegedly kicked the wing mirror of a vehicle.
A student had been charged with wilful damage after the Frederick St incident, Acting Senior Sergeant Ed Baker said.
