Police are investigating six armed robberies committed on Hungry Jacks restaurants over the past fifteen months.
Investigators believe that the same armed robber is responsible for all six robberies.
The first armed robbery happened on 24 June, 2011 in Burwood, when a man armed with a knife and a stick, entered the Hungry Jacks restaurant at 4.45am, jumped over the counter and demanded money from the staff.
The second incident happened four weeks later when the man returned to the same Burwood restaurant on 24 July, at 11.17pm, armed with a knife.
He again jumped the counter and demanded cash from the manager.
The third incident was at another restaurant on Canterbury Road, Forest Hill on 1 September, 2011 at 10pm when the offender entered the store, armed with a knife and stole an amount of cash, after threatening staff.
The man returned to the Burwood restaurant, for a third time, at 8.50pm on 4 November, 2011.  He jumped the counter, as in previous robberies, and stole an amount of cash after threatening staff.
On Friday 3 February, this year, at 6.25 am, the man targeted the Hungry Jacks restaurant on the corner of Blackburn and Highbury roads in Mount Waverley.
On this occasion, the man crawled through the window in the drive thru area and threatened staff before leaving with money from the till.
The last incident occurred on 24 August, 2012 at 6am when the man returned to his favourite restaurant on the Burwood Highway.
This time, the man threw a large rock through the front glass door and then crawled through the broken glass into the restaurant.
The man made off with an amount of cash and register drawers after threatening staff with a knife.
The man is described as being aged in his early 30s, and 172-175cm tall with a fair complexion and a medium build.
He was last seen wearing a black jacket, blue jeans and a black and grey scarf wrapped around his head.