A human rights group in Gaza has accused Hamas police of forcing men to shave their heads after saying their hairstyles were indecent.
The Palestinian Centre for Human Rights says several young men have been arrested for wearing their hair too long or with too much hair gel.
Officials from Hamas, the militant group that governs Gaza, denied this.
The human rights group says the men were beaten and forced to sign an agreement to keep their hair short.
They are also being forced to agree that they will not wear low-waisted trousers, the Palestinian Centre for Human Rights says.
If Hamas does want to crack down on hair gel and low-slung jeans it will have its work cut out.
Both styles are fashionable with young men in Gaza, where more than half the population is under the age of 18.
The Hamas-run interior ministry in Gaza has denied its police are involved and says Islamic student groups are responsible.
Witnesses to the arrests dispute this.
Critics of Hamas accuse it of increasingly imposing laws that reflect a conservative interpretation of Islam.
In the past Hamas has banned women from smoking shisha pipes and outlawed men from cutting women's hair. But both laws have never been fully enforced.
Some believe Hamas introduces such legislation to appeal to conservative elements in Gaza who consider the government to be too moderate.