Women with endometriosis are not getting diagnosed quickly enough and treatment is "unacceptable", say MPs.
The condition affects one in 10 women and can cause chronic pain, heavy periods, painful sex and depression.
More than 2,600 women spoke to the All Parliamentary Group on Women's Health with 40% saying they had seen a doctor 10 times before being diagnosed.
And many said they had to do their own research to understand the illness.
What is endometriosis?
Endometriosis is the name given to the condition where cells like the ones in the lining of the womb (uterus) are found elsewhere in the body - including the bowel, ovaries or bladder.
The cells act in the same way as during your period, building up and breaking down.
But they have no way of getting out of the body and can cause inflammation, pain and the formation of scar tissue.
Katie, 25, posts Instagram updates about endometriosis and the treatment she's getting.
Katie visited her doctor nine times before she was diagnosed with the condition.
"I went to the doctor so many times and I kept going back.
"There were things that they were throwing out there like IBS (Irritable Bowel Syndrome) or saying some people just get bad periods and you're just one of the unlucky ones."
"One doctor told me to stop doing sit-ups because it was all muscular.
"So I struggled a lot when I was at school and I would just pray that my period would come at the weekend so I wouldn't have to miss school and I wouldn't have to miss work."
Amy is 23 and a student at Oxford Brookes University.
It took doctors five years to diagnose her condition.
Her endometriosis got so bad last year she had to quit her job and had to stay in bed for several weeks.
What treatment is there?
At the moment there's no cure for endometriosis but symptoms can be treated.
Amy had a hormonal coil fitted which has helped her.
Others, like Katie, have had surgery to remove it - but it can grow back.
For many, it's just a case of treating the symptoms with pain killers.
Some women in the past have been told a hysterectomy (removing the womb) or having a baby can cure it, but there's no evidence to back those claims.
The new report says that treatment for women with endometriosis is currently unacceptable - with women being often dismissed by healthcare professionals.
It said 42% of women interviewed claim they were not treated with dignity and respect by doctors.
Why does it take so long to get a diagnosis?
It takes an average of seven and a half years to diagnose endometriosis.
In order to make a diagnosis, women have to have something called a laparoscopy. It's an operation in which a camera is inserted into the pelvis to look for any signs of endometriosis.
Professor Helen Stokes-Lampard from the Royal College of GPs says it's a tricky illness for GPs to identify.
"GPs face two major challenges here - both identifying condition that has very diverse symptoms and mimics lots of other things," she told Newsbeat.
"Also if we were to refer everybody with symptoms that could possibility be endometriosis, hospitals would be completely swamped and that wouldn't help the hospitals or the patients.
"Some patients would have operations they didn't need."
Word is getting out...
Celebrities like Girls creator Lena Dunham, Star Wars actress Daisy Ridley and singer Halsey have talked openly about their endometriosis.
Campaigners are now calling for better education on menstrual health in schools and improved training for GPs.
"The report highlights some really practical things we can do to reduce diagnose time and support women with this condition," Emma Cox, from Endometriosis UK, says.
That includes "education in menstrual health in schools" and "education for GPs and raising awareness with the public".