Cocaine abusers frequently report taking the drug in association with alcohol. This combined intake leads to the synthesis of cocaethylene, an active metabolite with effects similar to those of cocaine, but more prolonged. Since pharmacological effects of cocaethylene may partially account for the habit of cocaine abusers to take the drug in combination with ethanol, a main therapeutic goal in these patients should be making body fluids negative for cocaethylene. This randomized controlled open study conducted on 12 subjects co-abusers of cocaine and alcohol, evaluates the efficacy of a 12-week pharmacological treatment with Disulfiram (DIS) 400 mg daily or Naltrexone (NTX) 50 mg daily associated with Cognitive Behaviour Therapy (CBT), as compared to CBT alone, in terms of: (i) stay in treatment; (ii) drug-free urinalyses for cocaine and cocaethylene; (iii) reduction of alcohol and cocaine craving. Data presented in this study are restricted to the first 4 weeks of treatment when all the enrolled subjects were still available for examination. In fact, of the 12 subjects enrolled in the study only 4 (33%) completed the 12-week treatment. Of these, three were in the CBT group and one in the NTX/CBT group. Results show that CBT treated subjects remained in treatment longer than those assigned to either DIS/CBT or NTX/CBT therapies. However, during the first 4 weeks of treatment, CBT-group urine tested positive almost always for both cocaine and cocaethylene. In contrast, both DIS/CBT and NTX/CBT treatments were associated to a statistically significant reduction, of positive urinalysis for both cocaine and cocaethylene, with respect to CBT alone. Moreover, across the first 4 weeks of treatment DIS/CBT and NTX/CBT treated subjects maintained lower scores at Visual Analogue Scales (VAS) for both cocaine and alcohol craving than subjects receiving CBT alone. This pilot study suggests that the transient efficacy of pharmacological treatments in maintaining subjects drug free, does not add to the capability of CBT to retain them in treatment.