T-lymphocyte subpopulations were measured in the two major types of adult malnutrition, adult marasmus and kwashiorkor-like hypoalbuminemic malnutrition. The population of T-cells (T3) and the percentage of both helper (T4) and suppressor (T8) T-cells were significantly (P less than .05) decreased in patients with kwashiorkor-like hypoalbuminemic malnutrition, but did not differ from control values in patients with adult marasmus. The ratio of helper T-cell (T4), to suppressor T-cells (T8) (range 1.2-1.6) did not vary from control values in either type of malnutrition. One week of nutritional support was not associated with a significant increase in any of the T lymphocyte subpopulations in either type of malnutrition. These T-cell subpopulation changes are consistent with the greater depression of cellular immune function seen in patients with metabolic stresses associated with kwashiorkor-like hypoalbuminemic malnutrition. With the increasing frequency in which abnormalities of T-cell subpopulations are being reported in various diseases, the coexistence of kwashiorkor-like hypoalbuminemic malnutrition should be noted for its potentially confounding effect.