Background:
Many studies have reported on the use of the Internet for the purpose of finding sex partners. Trend data on this behavior are lacking.

Objective:
To describe characteristics of patients reporting having sex with a partner they met on the Internet in two cross-sectional studies conducted in the same STD clinic 7 years apart.

Method:
Between September 2000 and May 2001, patients attending the Denver Metro Health Clinic (DMHC) were administered a 10-item survey on Internet sex seeking. Since August 2006, patients attending the same clinic are routinely asked about Internet sex partners.

Result:
Of 14,887 patients seen at DMHC between September 2006 and September 2007, 1,784 (12.0%) reported ever having sex with a person they met on the Internet, compared to 146 of 2,159 (6.8%) on the 2000-2001 survey. For the two time frames, the proportions of patients finding sex partners online increased from 28.6% to 46.2% for men who have sex with men (MSM), from 4.4% to 5.7% for men who have sex with women, and from 1.3% to 3.6% for women. For age categories, the proportions increased from 4.0% to 4.4% among <20 year olds (yo), from 5.6% to 9.3% among 20-29 yo, from 7.6% to 15.9% among 30-39 yo, from 10.7% to 19.2% among 40-49 yo, and from 4.9% to 17.1% among >= 50 yo patients.

Conclusion:
Although the data collection methods differed, there appears to be an overall increase in the proportion of STD clinic patients reporting sexual encounters with a person they met on the Internet, with relatively higher increases among MSM and patients older than 30.

Implications:
Over the past decade, an increasing proportion of patients visiting DMHC are finding sex partners online. Implications of this behavior for transmission and prevention of sexually transmitted infections should be investigated.