This chapter explores the feasibility of collecting biomarkers in Internet surveys. First, we present an overview of biospecimens and biomarkers collected in population surveys. Second, we report the results of a pilot in the Netherlands to examine the feasibility of collecting blood cholesterol (n=200), saliva cortisol (n=200) and waist circumference (n=200) in the LISS Internet panel. Participation rates were 15.5% for cholesterol, 26.5% for waist circumference and 15.0% for diurnal salivary cortisol. Despite low response rates, participants were able to take measures using self-test devices guided by video instructions, and biomarker values corresponded with expected ranges and means. Collecting biomarkers in an Internet survey is potentially feasible, but strategies need to be developed to increase response and participation rates.