448 sera from patients with amoebic dysentery or liver abscess were taken before treatment and at varying intervals after treatment and were tested by the indirect haemagglutination test (IHA) and by microimmunoelectrophoresis (MIEP). All the sera showed one of 7 patterns; the maximum response (pattern 1) showed 14 arcs and the minimum only 2 (pattern 7). 96% of sera showing pattern 1 were taken before or within 2 months after treatment; pattern 7 persisted longest and was found throughout the period of observation. Pattern 1 correlated with high IHA titres, and through to pattern 7 the IHA titres tended to be lower, until with pattern 7 several showed negative IHA tests. The combination of the MIEP pattern and IHA titre level is claimed to provide differentiation between an active infection and antibodies persisting after cure; if the titre level is high and MIEP pattern 1, 2 or 3 is observed it can be predicted almost with certainty that the infection is active. W. P. Stamm.