To determine the impact of the Olympic Games the Sydney Sexual Health Centre database was accessed for demographic, health care utilization, and morbidity variables for two periods of interest: 15-29 September 2000 (the 'Olympic period'), and 1-30 September 1999 ('1999 comparison period'). Differences were tested by chi-square statistics and by calculation of odds ratios (ORs) using SPSS. During the Olympic period twice as many of the new patients had arrived in Australia that year (35% c.f. 18%: OR 2.46, 95% CI 1.49-4.05, P=0.0002). Per attendance the proportion with symptoms or a known sexually transmitted infection (STI) contact was higher during the Games (29% c.f. 16% OR 1.67, 95% CI 1.1.27-2.21, P=0.0002) and there was a marginally higher yield of bacterial STIs (6% c.f. 3%: OR 1.83, 95% CI 1.06-3.13 P=0.03). The normal clinic population was replaced by an increased proportion of symptomatic patients who were recent arrivals in Australia.