We investigated the association between the presence, severity, and frequency of dysmenorrhea, acyclic pelvic pain, and dyspareunia, as well as the presence of pain with bowel movements, and circulating cytokine and chemokine (C-reactive protein (CRP), IL-1β, IL-6, IL-8, IL-10, TNF-α, monocyte chemotactic protein (MCP)-1, MCP-4, thymus and activation-regulated chemokine (TARC), IL-16, interferon gamma-induced protein (IP)-10) levels among adolescents and adults with and without endometriosis. The gene discussed is CRP; the disease is endometriosis.