Endometriosis affects around one in ten women of reproductive age in the UK. NICE guidance highlights the importance of symptoms in its diagnosis. A normal abdominal or pelvic examination, ultrasound, or MRI should not exclude the diagnosis. Endometriosis should be suspected in women and adolescents who present with one or more of: chronic pelvic pain, significant dysmenorrhoea, deep dyspareunia, period-related or cyclical GI or urinary symptoms, or infertility. If endometriosis is suspected or symptoms persist, patients should be referred for further assessment.