The pharmacokinetics and the dose proportionality of a new anticonvulsant compound, HEPP (D,L-3-hydroxy-3-ethyl-3-phenylpropionamide) was studied in healthy male volunteers as part of the pharmacological evaluation for new drugs. Study was performed administering doses of 250, 375, 500 and 625 mg of HEPP to six male volunteers. Blood and urine samples were collected for 72 h postdose and analysed by HPLC. Results showed that in man HEPP is rapidly absorbed from the gastrointestinal tract. Tmax values were between 1.5 and 6.0 h. Plasma mean terminal half-life after the different doses ranged between 15.83 and 27.62 h with an overall harmonic mean value of 22.8. The mean AUC0-infinity and Cmax increased linearly with doses of 250, 375 and 500 mg but not with the dose of 625 mg. The amount of unchanged drug excreted in urine was between 3 and 6% of administered dose which shows an extensive metabolism of the drug.