In this study, we evaluate national HIV prevalence estimates from DHS and AIS surveys for bias resulting from non-response in the surveys. Data are from 17 recent national DHS and AIS surveys with HIV testing conducted during 2001 and 2006. Blood samples were collected and tested for HIV using standard laboratory and quality-control procedures. For each of the 14 countries with HIV serostatus data linked to individual characteristics and behaviors, we predict HIV prevalence among non-responding adults on the basis of multivariate statistical models of HIV for those who were interviewed and tested, using a common set of predictor variables. In the 14 countries with linked data, the HIV testing rate varied from a low of 63 percent among men in Malawi and Zimbabwe to a high of 97 percent among women in Rwanda. Non-response rate was higher among urban, more educated, and wealthier men and women but had no clear association with various risk and protective behavioral factors. Although non-tested men and women tend to have higher predicted HIV prevalence than those tested, the overall effect of non-response bias on observed prevalence estimates was small and not significant in all countries. In the 14 countries, HIV prevalence estimates adjusted for non-response bias were on average only 3 percent and 2 percent higher than the observed, non-adjusted estimates for men and women, respectively. The study finds that non-response for HIV testing tends to have small, non-significant effects on national HIV seroprevalence estimates obtained from national household surveys.