The main problems in solid organ transplant recipients are rejection and infections. The new immunosuppressive regimens have lowered the risk of rejection, however, infections continue to be one of the most important determinants for morbidity and mortality in these patients. The survival of the transplanted organ is also impacted by the different infectious diseases that occur in the post-transplant period. These infections are of viral, bacterial, fungal and parasitic origin, and their presentation occurs characteristically within well defined risk periods after the transplant. The clinical presentation is commonly atypical; therefore for optimal management, it is necessary to have a through knowledge of the epidemiology and clinical manifestations of these problems, but most importantly, the experience of the clinician in the clinical approach and early detection will result in better outcomes. We review recent information regarding the infectious diseases that affect solid organ recipients according to the type of transplant, the post-transplant, risk factors before the transplant and the type of immunosuppressive therapy used, which are the main determinants for these complications and their prognosis.