The objective of this study is to search for a selective active surfaces in adsorption of some drugs that cause poisoning when taken orally at high doses.Three drugs have been chosen: amitriptyline HCI, chlorpromazine HCI, and chloriazepoxide HCI. A comprehensive study of adsoiption of these drugs in aqueous solutions on locally available three Iraqi clays (kaolin, bentonite. and attapulgite) has been carried out. U.V. spectrophotometnc technique has been utilized to produce quantitative adsorption data at different temperatures (5, 20. 37.5 and 50 °C). The effect acidity on the quantity adsorbed of these drugs was investigated at PH=1 in an attempt to simulate the acidity of gastric fluid. The possible effects of ionic strength on the amount of drugs being adsorbed was studied using normal saline solution and magnesium sulfate solution. The results obtained from this study can be summarized as : 1. The activity of the surfaces in adsorbing the drugs mentioned above was found to follow the order: Attapulgite bentonite kaolin. This order remained unchanged with changing the temperature, PH. and i strength. 2.Adsorption of chlordiazepoxide HC1, chlorpromazine HC1, and Amitriptyline HC1 on kaolin surface followed the following order in neutral medium at 37.5°C chlorpromazine HC1 amitriptyline HC1 chlordiazepoxide HC1 but the adsorption of these drugs on attapulgite and bentonite surfaces obeyed the sequence amitriptyline HC1 < chlorpromazine HC1 chlordiazepoxide HC1. 3.tHE AMOUNT OF CHLORDIAZEPOXIE HCI being adsorbed on the tree clays deceased with decreasing PH. Inversely, the quantity adsorbed of amitriptyline HCI increased on kaolin and bentonite surfaces but decreased on attapulgite surface as the value of PH decreased 4. The adsorption, generally, increased with increasing the ionic strength of the solution. 5. Adsorption of ehlorprornazine HC' on the three surfaces is endothermic process, but the adsorption of chlordiazepoxide HC1 and amitriptyline HC1 was exothermic process. The results of this study were discussed in the light of Freundlich and Langmuir adsorption isotherms. The usual thermodynamic quantities were calculated in order to interpret these results.