This study was undertaken to investigate the bioavailability of various L-carnitine esters (acetyl-L-carnitine and lauroyl-L-carnitine) and salts (L-carnitine L-tartrate, L-carnitine fumarate, L-carnitine magnesium citrate) relative to base of free L-carnitine. Six groups of five or six piglets each were administered orally a single dose of 40 mg L-carnitine equivalents/kg body weight of each of those L-carnitine compounds. A seventh group served as a control. Free and total plasma carnitine concentrations were determined 1, 2, 3.5, 7, 24, and 32 hours after administration of the single dose. Area-under-the-curve (AUC) values were calculated to assess the bioavailability of the L-carnitine compounds. AUC values, calculated for the time interval between 0 and 32 hours, for both free and total carnitine were similar for base of free L-carnitine and the three L-carnitine salts (L-carnitine L-tartrate, L-carnitine fumarate, L-carnitine magnesium citrate) while those of the two esters (acetyl-L-carnitine, lauroyl-L-carnitine) were lower. Administration of L-carnitine L-tartrate yielded a higher plasma free carnitine AUC value for the time interval between 0 and 3.5 hours than administration of the other compounds. The data of this study suggest that L-carnitine salts have a similar bioavailability to that of free L-carnitine while L-carnitine esters have a lower one. The study also suggests that L-carnitine L-tartrate is absorbed faster than the other L-carnitine compounds.