A pressure chamber was used to compare microleakage associated with complete metal crowns cemented to extracted teeth using three different luting agents. Complete crowns were cemented on 60 extracted premolar teeth: 20 were cemented using a zinc phosphate cement, 20 usin g a glass-ionomer cement, and 20 using a resin cement. Following 7 days of storage in normal saline, each of the teeth in the experimental groups was pressure cycled 15 times, during which time the occurrence of microleakage was monitored. Microleakage was found to occur in crowns cemented with the zinc phosphate and glass-ionomer cements; no microleakage was detected with the resin-cemented crowns. Microleakage was also found to occur sooner and to a greater extent with zinc phosphate than with glass-ionomer cement.