Bailey AP, Hill AS, Beste MT, et al. - Researchers aimed at comparing the inflammatory‐ and immune‐associated peritoneal cytokines of adolescents and adults with and without endometriosis via performing a nested case‐control study in multiple university‐affiliated scientific centers. Laparoscopic aspiration of peritoneal fluid (PF) was performed in 10 adolescents and 13 adults with visually and histologically confirmed endometriosis (cases), 13 adolescents with visually suspected endometriosis but indeterminate (seven patients) or negative (six patients) histology, and 15 adults undergoing surgery for non‐malignant gynecologic disease without endometriosis (controls); from these, they assayed PF and conditioned medium (CM) cytokine levels. Relative to adults with endometriosis, adolescents with endometriosis had significantly higher MCP‐3, IL‐12p40, MIP‐1β, and IL‐15, while lower TNF‐β and CTACK were observed among adolescents. Similar differences were observed when adolescents with endometriosis were compared with adult controls except for MIP‐1β, which was not statistically different. However, MIP‐1β was noted to be the only cytokine differing between adult cases and controls. Findings thereby suggest existence of biologically relevant and statistically significant differences in six PF cytokines and indicate a more pro‐invasion cytokine profile among adolescents with endometriosis. They revealed unique peritoneal cytokine profiles and molecular behavior among adolescents with endometriosis compared with adults with and without endometriosis.