Pre-print, Working paper: This paper estimates the hidden cost of informal redistribution in urban Senegal. It is based on a lab-in-the-field experiment combined with a small-scale randomized controlled trial. We show that two-thirds of the experiment participants are ready to forgo up to 14% of their lab gains to keep them private. When they are given the opportunity to hide, they decrease by 27% the share of gains they transfer to kin and increase health and personal expenses. This is the first paper to identify the individual cost of informal redistribution and to relate it to real-life resource-allocation decisions in a controlled setting.