Screening may not be the best next step Population based screening for asymptomatic Chlamydia trachomatis infection has been postulated since the introduction of nucleic amplification techniques that enable testing on non-invasive samples.1 Screening also seems logical because the infection is common and curable, and asymptomatic, and symptomatic infections are thought to be important causes of pelvic inflammatory disease and other complications of the female reproductive system.2 In the linked cluster randomised trial with a stepped wedge design (doi:10.1136/bmj.e4316), van den Broek and colleagues report on the effectiveness of screening in more than 300 000 Dutch men and women.3 The study provides important new information on the feasibility of screening. The results are disappointing and suggest that the strategy should be reconsidered. Over the course of three rounds of screening the participation rate fell from 16.1% to 9.5%. In addition, 4.2% of participants were C trachomatis positive at the first invitation and there was only …