Despite their common history, there are many cultural, attitudinal and practical differences between the professions of medicine and pharmacy that ultimately influence patient care and health outcomes. While poor communication between doctors and pharmacists is a major cause of medical errors, it is clear that effective, deliberate doctor-pharmacist collaboration within certain clinical settings significantly improves patient care. This may be particularly true for those patients with chronic illnesses and/or requiring regular medication reviews. Moreover, in hospitals, clinical and antibiotic pharmacists are successfully influencing prescribing and infection control policy. Under the new Irish Pharmacy Act (2007), pharmacists are legally obliged to provide pharmaceutical care to their patients, thus fulfilling a more patient-centred role than their traditional "dispensing" one. However, meeting this obligation relies on the existence of good doctor-pharmacist working relationships, such that inter-disciplinary teamwork in monitoring patients becomes the norm in all healthcare settings. As discussed here, efforts to improve these relationships must focus on the strategic introduction of agreed changes in working practices between the two professions and on educational aspects of pharmaceutical care. For example, standardized education of doctors/medical students such that they learn to prescribe in an optimal manner and ongoing inter-professional education of doctors and pharmacists in therapeutics, are likely to be of paramount importance. Here, insights into the types of factors that help or hinder the improvement of these working relationships and the importance of education and agreed working practices in defining the separate but inter-dependent professions of pharmacy and medicine are reviewed and discussed.