This paper studies the effect of proposing a monetary incentive for vaccination intentions, with a survey-based randomized controlled experiment conducted separately in three countries, Tajikistan, Uzbekistan, and Kazakhstan. Respondents from nationally representative surveys were randomly assigned to a control group (for which no incentive was proposed) or to one of several treatment groups with varying levels of hypothetical compensation. Offering incentives markedly reduced overall vaccination intentions -all three counties. Country-level results ranged from no meaningful effect on vaccination intentions (Tajikistan) to a decline of up to 22 percent (Uzbekistan and Kazakhstan). In follow-up questions, most respondents said they disapprove of offering financial incentives for vaccination, and especially in contexts with strong negative effects in the experiment. The results contrast with the well-established efficacy of monetary incentives to influence vaccination behavior in other settings, but they are consistent with findings from the behavioral literature in which incentive payments signal inferiority or disutility. The findings suggest that policy makers and practitioners should use caution when considering extrinsic incentives for vaccination and other health interventions where effects have not been tested.