The effect of the concentration of plasma protein on the recovery from anaesthesia induced by equipotent doses (UD95) of thiopentone and Althesin was studied in 48 patients. The recovery time (RT) wa plotted against the concentrations of total plasma proteins (TPP) and albumin (Al). A small decrease in TPP concentration from normal range affected the recovery time minimally; a small decrease in TPP concentration from a low basal value markedly increased the recovery time with both agents. A large decrease in TPP concentration increased the recovery time from thiopentone and Althesin markedly.