The accuracy and consistency of the delivery of ethanol to cultured cells is important to determine effects on morphologic, biochemical and physiologic alterations. Open and closed chamber systems were evaluated to determine cytotoxic vs sublethal, potentially teratogenic effects on neonatal rat cardiac myocytes. The open system employed a variety of cell culture vessels. Cardiac cells were exposed directly to ethanol in the growth media at concentrations of 5-50 mM in Petri dishes, multiwell slides and multiwell chambers. Ethanol concentrations in the media in these open vessels decreased over 60% in a 24 hr incubation period. A closed system consisted of tightly sealed plastic containers in which the same vessels were used. The vessels were placed on a platform over a bath of ethanol-water. Cells were acclimated for 24 hr with ethanol in the bath at 200% of the final desired media concentration. Ethanol gradually diffused into the media to reach peak levels of 5, 10, 25 or 50 mM at 24 hr. After the 24 hr period, ethanol was added to both the media and bath at the desired concentration. Cells exposed gradually to ethanol in the closed chambers remained viable, but showed slower division and growth. A period of gradual acclimation is required to induce sublethal cellular effects rather than lethal effects. The diversity of cell systems and manipulations of cultures to study the potential teratogenic effects of ethanol are improved using such a closed chamber system.