Relocation stress may be one factor increasing the mortality rate of people who are severely and profoundly retarded (S/P MR) when they transfer from institutional to community living arrangements. However, no research exists concerning acute stress effects with groups who are S/P MR. In this project, 28 residents of a state facility for those with S/P MR were exposed to five-minute structured educational tasks. Venous blood samples were drawn before and after the stressor. Granulocytes, red blood cells, hemoglobin, and plasma protein increased while monocytes decreased after stress. Immune cell subsets did not change significantly. Hemoconcentration, an important factor in thrombosis and ischemia, may relate to relocation stress in S/P MR populations. Methodological factors limit generalization but additional research with larger samples, more indices of stress, more poststress blood samples, and additional stressors are encouraged.