We investigated the effectiveness and cost-effectiveness of pessary treatment compared with pelvic floor muscle training (PFMT) in women with pelvic organ prolapse over a 2-year period. Randomized controlled trial with women (≥55 y) with symptomatic pelvic organ prolapse, identified by screening. Participants were recruited from 20 primary care practices (October 2009-December 2012). Primary outcome was the difference in change of pelvic floor symptoms (PFDI-20 score) between groups over 24 months. Secondary outcomes included prolapse, urinary, and anorectal symptoms; quality of life; costs; sexual functioning; prolapse stage; pelvic floor muscle function; and participants' perceived symptom improvement. There was a nonsignificant difference in the primary outcome between pessary treatment (n = 82) and PFMT (n = 80) with a mean difference of -3.7 points (95% CI, -12.8 to 5.3; P = 0.42) in favor of pessary treatment. A significantly greater improvement in the prolapse symptom score was, however, seen with pessary treatment (mean difference -3.2 points [95% CI, -6.3 to -0.0; P = 0.05]). Direct medical costs over the 2-year study were $309 and $437 per person for pessary treatment and PFMT, respectively. In older women with symptomatic prolapse, there was no significant difference between pessary treatment and PFMT in reducing pelvic floor symptoms, but specific prolapse-related symptoms did improve more with pessary treatment. Pessary treatment was preferable in the cost-effectiveness analysis. When counseling women for prolapse treatment it should, however, be taken into account that pessary fitting fails in a considerable portion of women and that pessary treatment was associated with more side effects compared with PFMT.