A 16 year-old girl was able to buy 100 cigarettes unchallenged from vending machines in Solihull town centre and Knowle in an exercise organised by Solihull Council and Solihull NHS Care Trust.
The initiative demonstrated the ease with which young people can buy cigarettes from vending machines - a situation the Government is hoping to control.
Cabinet Member for Quality of Life and Neighbourhoods, Councillor Diana Holl-Allen said: "We work hard with traders to make sure they understand the importance of not selling tobacco products to underage people.
"It's disappointing to learn that some are not being vigilant about the people using their vending machine.
"We urge all traders who have a cigarette vending machine on their premises to think about where it is situated and to ensure staff challenge anyone using the machine who may be underage."
Alison Trout, Stop Smoking Manager, Solihull NHS Care Trust added: "Smoking is dangerous at any age, but the younger people start, the more likely they are to smoke for longer and to die early from smoking. Someone who starts smoking aged 15 is three times more likely to die of cancer due to smoking than someone who starts in their mid-twenties."
Figures from the British Heart Foundation indicate more than one in six children who smoke regularly buy their cigarettes from machines.
For help in quitting smoking call Solihull NHS Care Trust on 0121 712 8333.