Introduction Women with endometriosis have reduced health‐related quality of life (HRQoL). However, comparisons to the general population and other patient groups are lacking. Material and methods The present cross‐sectional questionnaire study included 157 women with endometriosis, 156 women from the general population, and 837 women with rheumatoid arthritis (RA). During a period from 2012 to 2013, women aged 18‐45 years were recruited from the Norwegian Endometriosis Association and from a random sample of women residing in Oslo, Norway. HRQoL data from women with RA were included from a survey conducted in 2009 among patients of the Oslo Rheumatoid Arthritis Register. The Short Form‐36 (SF‐36) questionnaire was used to measure HRQoL. Results Compared with the control group, the endometriosis group had significantly reduced mean scores for all SF‐36 scales. The difference was largest for the scale bodily pain with a mean score of 47.6 in the endometriosis group vs 81.5 in the control group. Compared with the RA group, the endometriosis group had significantly reduced mean scores for the three SF‐36 scales vitality, social functioning, and mental health. The mean scores of these scales in the endometriosis group were 33.4, 62.7, and 66.3, respectively, vs 42.7, 68.8, and 72.6 in the RA group. Conclusions Women with moderate to severe endometriosis seem to have overall impaired HRQoL compared with women from the general population, and poorer mental HRQoL compared with women with RA.