Two derivatives of erythromycin, the stearate and the enteric-coated base have been given in a cross-over study to both fasting and non-fasting volunteers. The stearate gave higher plasma concentrations in non-fasting than in fasting subjects. The area under the curve was significantly larger during steady state day 7 than after a single dose. The base showed larger individual variations in concentrations. The release of the drug from the enteric-coated tablets was depressed by food, but the absorption was not prevented.