Objectives: In Victoria, Australia, legislation requires sex workers to undergo monthly testing for gonorrhoea, chlamydia and trichomonas, and 3-monthly for HIV and syphilis, despite extremely low rates of sexually transmitted infections (STI) in female sex workers (FSW). The aim of this study was to quantify the resources and opportunities lost from this screening. Methods: Computerised medical records of patients attending the Melbourne Sexual Health Centre (MSHC) between October 2005 and October 2008 were reviewed. Results: Consultations with FSW accounted for 15.1% of total consultation time (5722 of 37 670 h) and of these, 2896 h (7.7%) were used for monthly consultations involving testing for gonorrhoea, chlamydia and trichomonas, but no serology (termed swab-only testing). Only 133 (3.2%) of the 4208 cases of STI (defined as gonorrhoea, chlamydia, trichomonas, early syphilis, mycoplasma genitalium or HIV) that were detected at MSHC during the study period were among FSW who underwent swab-only testing. 1726 (41%) STI were detected among men who have sex with men (MSM). The STI detected per 100 h of consultation time was (fourfold) higher for MSM (19) than for FSW (4). If FSW were tested only every 3 months for gonorrhoea, chlamydia, trichomonas, syphilis and HIV the 2896 h spent on monthly swab-only testing would have been available for higher-risk clients Conclusion: The current legislation requiring monthly STI testing is compromising the access for higher-risk individuals to sexual health. Other countries contemplating mandatory testing need to consider the influence that the frequency of testing has on access to sexual health services for high-risk groups.