Gillian Anderson has revealed that she's had romantic relationships with women.

The 43-year-old actress opened up about her lesbian experiences in the April issue of Out magazine.

Gillian, best known for her role as Agent Scully on The X Files, told the publication that she now feels comfortable to talk about her same-sex flings.

"I was in a relationship with a girl for a long time when I was in high school," she revealed.

"You know, I'm old enough that I can talk about that."

Gillian has been divorced twice after failed marriages to Clyde Klotz and Julian Ozanne and has been dating partner Mark Griffiths for six years. She has a 17-year-old daughter, Piper, and two sons; Oscar, five, and Felix, three.

The actress added that her gay experiences were not a big deal because she knew that she also liked men.

"If I had thought I was 100 per cent gay, would it have been a difference experience for me?" she questioned.

"Would it have been a bigger deal if shame had been attached to it and all those things that become huge life-altering issues for youngsters in that situation?"

"It's possible that my attitude around it came, on some level, from knowing that I still liked boys."

Gillian also listed the other kinds of people that she dated in the past.

"[They've included] a punk drug addict [and] somebody who was way, way older than me," she shared.

"Everything that that kind of anarchistic attitude brings the inappropriate behaviour it leads to was how I chose to be in the world at that time, which was, you know, not what people did."

Gillian stars in the BBC adaptation of Charles Dickens' Great Expectations.