The pharmacokinetic behaviour and bioavaitability of doxycydine were determined in experimentally B₁ aflatoxicated Baijin duddings and in healthy ones following a single intravenous (iv) , intramuscular (i.m) and oral administration of 20 mg/Kg bodymeight of doxycydine hydate . Tissue residues of the tested drug after an oral dose of 26rrig/Kg bodyweight given twice daily for 5 consecutive days were also estimated . Moreover, its effects on body weight and serum liver enzymes were also studied . Ei_l aflatoxicosis resulted in a significant decrease in doxycydine serum concentration in aflatoxicated Baijin duddings than those recorded in healthy ones following a single iv , i.m and oral administration. Following a single i.v injection, the concentration time curve was fitted to follow the three compartments open model with elimination half lives (t_os 08.24* 0.09 and 7.32* 0.07 hours) in healthy and aflatoxicated Bair duddings respectively. Higher volume of distribution at steady state (Vd,) and total body dearance (C _tct) were recorded in aflatoxicated Baijin duddings (2.22±0.10 L/Kg and 0.25±0.001L/h/kg) than healthy ones (1.5±0.36Lfirg and 0.14*0.0081/h/Kg). Lower values of systemic bioavailablity were observed in aflatoxicated 8aijin duddings (72.7±2.1 %and 45.93±3.2%) than healthy ones (92.5*4.0%and 50.3±4.1%) after oral and intramuscular administration, respectively. After single oral administration , the absorption half life (t_oss) and elimination half life (tosk,$)were longer in healthy duddings (0.641-0.01 and 11.09*0.84hour) than in aflatoxicated ones (0.45±0.03 and 7.731-0.87hour). The maximum serum concentration of the drug was higher in healthy duddings than aflatoxicated ones. The highest concentrations of doxycydine were present in kidney and liver, and the lowest concentrations were present in heart and musdes. The drug was completely disappeared from all edible tissues 7 days after the last dose of repeated oral administration. So, the administration of the drug must be discontinued for at least 7 days before slaughter.