A pharmacokinetic profile of ¹⁴C-AdDP with uniformly labelled alanine was investigated. It was shown that the distribution phase after an i.v. administration is very short with a half-life of 2.1 min. the half-life of elimination phase after the i.v. administration is about 2.85 hours, that is longer than those of MDP and its derivatives. the total body clearance (30 ml/min/kg) is caused predominantly by metabolism of the compound. All the radioactivity found in urine in a 48 hours interval after a s.c. administration represents only 3.1% of the administered dose. Only a smaller part of the excreted radioactivity is formed by unmetabolised AdDP. the concentration curve after a S.C. administration is characterized by a very fast absorption with a half-life shorter than 1 minute. the distribution and elimination phases are prolonged (20 min, 11 hours respectively) in comparison with an i.v. injection. the decreased absolute bioavailability after a s.c. administration (65%) is probably not biologically significant because of a slower release of the compound from the site of the S.C. administration. A relatively very high radioactivity was found in liver, kidney, thymus, spleen and brain very soon which suggest a very good penetration into tissues. It is an agreement with the high apparent distribution volume of peripheral compartment and higher lipophilicity of AdDP as compared to MDP.