Penelope Cruz likes Alia dresses because he "really knows the body of a woman".
The Spanish actress wears one of Tunisian-born designer Azzedine Alaia's designs in a shot for the 2013 calendar for drinks brand Campari, and she has long been a fan of his work.
She told Vogue magazine: "I liked so many of the dresses but I'm a huge fan of Alaia. I think he really knows the body of a woman."
The 38-year-old 'Pirates of the Caribbean: On Stranger Tides' star has also designed items herself, working alongside her sister, Monica on a handbag range for Japanese store Samantha Thavasa, a collection for Mango and a line for lingerie brand Agent Provocateur, which will launch in 2013.
She said: "It's great working with my sister, because we are very close as a family, my brother, my sister and myself. We have a great relationship. It's a blessing because you want to be together as much as possible, so to work together is really great."
Moonlighting as a designer has also given Penelope a greater appreciation for the design industry.
She added: "There are so many designers that I love, and I'm so lucky that I get to work with so many of them and sometimes spend time with them. As an actress you get to go to these events and wear their things - it's fun but it is what it is. I don't put a lot of time into it but I respect what they do.
"There's a lot of work that goes into it - if you think about how many collections a year that Karl Lagerfeld has to do, with Chanel and all the other things he does - you can't do that unless you are working 18 hours a day. It's really a lot of hard, hard work."