BackgroundAlthough the increasing dissemination and use of health-related information on the Internet has the potential to empower citizens and patients, several studies have detected disparities in the use of online health information. This is due to several factors. So far, only a few studies have examined the impact of socio-economic status (SES) on health information seeking on the Internet. This study was designed to identify sociodemographic and health-(care-)related differences between users and non-users of health information gleaned from the Internet with the aim of detecting hard-to-reach target groups.MethodsThis study analyzed data from the NRW Health Survey LZG.NRW 2011 (n = 2,000; conducted in North Rhine–Westphalia, Germany, via telephone interviews). Logistic regression analysis was used to examine the determinants of online health information seeking behavior.Results68% of Internet users refer to the Internet for health-related purposes. Of the independent variables tested, SES proved to exert the strongest influence on searching the Internet for health information. The final multivariate regression model shows that people from the middle (OR: 2.2, 95% CI: 1.6–3.2) and upper (OR: 4.0, 95% CI: 2.7–6.2) social classes are more likely to seek health information on the Internet than those from the lower class. Also, women are more likely to look for health information on the Internet than men (OR: 1.5, 95% CI: 1.1–2.1). Individuals with a migration background are less likely to conduct health searches on the Internet (OR: 0.6, 95% CI: 0.4–0.8). Married people or individuals in a stable relationship search the Internet more often for health information than do singles (OR: 1.9, 95% CI: 1.2–2.9). Also, heavy use of health-care services compared to non-use is associated with a higher likelihood of using the Internet for health-related matters (OR: 1.7, 95% CI: 1.2–2.5).ConclusionsIn order to achieve equity in health, health-related Internet use by the socially deprived should be promoted through measures to increase their level of e-health literacy. Furthermore, longitudinal studies are needed in order to gain reliable data/results on determinants of health-related Internet use.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-015-1423-0) contains supplementary material, which is available to authorized users.