The present study is descriptive, retrospective type and cross-section, and it was developed with the purpose of determining the medicaments interactions in the treatment of Deep Vein Thrombosis (DVT) in the patients hospitalized in the services of Medicine "C" and Surgery "A" of the Hospital Regional Docente de Trujillo (H.R.D.T.). 55 Clinical Histories were reviewed of which the 69,1% (38 patients) carry out the inclusion requirements. Of these was analyzed 281 prescriptions/day of hospital stay, which were put under evaluation to determine the medicamentosas interactions that they appeared in prescriptions/day by means of the analytical bibliographical method. Of the 38 analyzed Clinical Histories, it found that the 61,57% of prescripciones/día (173) presented medicaments interactions; being the most frequent Warfarin - Heparin (20.46%), Warfarin - Dalteparin (5.76%), Warfarin - Tram...