Henna tattoos are definitely a must do when in Morocco.
I am one of those travelers that if I have the time I google and (attempt) to research EVERYTHING before I go. I really wanted to get henna done while in morocco but I had heard horror stories about the experience and how it sometimes can be a scam. (More about Marrakesh scams here) Between not getting a good artist or paying a ton of money for something that washed off after two showers I was a bit skeptical. Thankfully every time I googled henna and Marrakesh together I got the same results ‘Go to Henna Café’.
Henna Café is first off a great organization that is a registered cultural foundation in morocco. All the income they generate is used to provide free education and assistance to the local people.
The café also specializes in authentic henna with all natural red dye. The henna artists are local women and the designs in their book are all from local artists. They also make sure they give the tattoo's proper after care with a bit of lemon water and you also receive a protective sleeve for your arm as well.
The tattoos start as low as 50DH and go all the way up to 500DH depending on the intricacy of the design you choose. For reference I got a full arm henna tattoo and it only cost 200DH. Kelly's was about 150DH.
The café is sometimes hard to find. Below is a map from the main square to the café. I suggest the outside route highlighted in blue because the slightly quicker inside route takes you through the souk and is very easy to get lost in.
Once you arrive you go up the stairs to the very top floor. The food is excellent and very fresh. You also can play with their two resident turtles while at the café but be careful! Their bigger turtle has been known to climb into bags and try to hitch a ride home with people!