A national opportunistic chlamydia screening programme, mainly targeting young sexually active women, is gradually being introduced across the UK and in future will predominantly occur in primary care sites. The relative efficacy of recommended antibiotic treatments for chlamydia has been poorly studied and especially that of single dose azithromycin. In Portsmouth, 1536 patients treated for chlamydia, with four different antibiotic regimens, during the Department of Health pilot study, were asked to return for test of cure. No difference in treatment outcome was found using doxycycline, oxytetracycline, erythromycin or azithromycin. Directly observed therapy with azithromycin may be especially helpful in treating young chlamydia-positive patients.