Hospitalizations of foreign patients from developing countries outside the European Union were examined for the period 1999-2004, focusing on infectious diseases and on pregnancy issues. Patients over 14 years old had 6,003 admissions, leading to 7,231 overall diagnoses. During the 6-year study period, female hospitalizations increased steadily, with a peak in 2002 (p .001). This trend was mainly due to the rise in women from Eastern Europe (p .001), which occurs at a younger mean age versus that of males (p .001). Admission of illegal immigrants, performed on an emergency basis, accounted for an average of 9.4%. This phenomenon was very frequent in 1999 (43% of admissions), but dropped sharply after 2002 (p .001), caused by changes in Italian law. The prevalent women diagnoses were ob/gyn ones: voluntary pregnancy interruption, spontaneous abortion or pregnancy complications in 30.6% of cases, and childbirths or controls of pregnancies with a favourable outcome in 18.2% of patients. These diagnoses covered nearly 50% of hospitalizations of migrant women: other admissions were due to organic, dysmetabolic, or functional disorders, while infectious diseases were less frequent (4.6%). Among men, dysmetabolic disorder and organic-degenerative diseases, or functional illnesses (36.2%), were prominent, and significantly more frequent versus women (p .001), as well as post-traumatic diseases (16.5%), and infectious illnesses (12.1%; p .001). Also generic-undefined diagnoses were proportionally numerous (6.6%): cultural-language deficiencies affected the physician-patient relationship. Among infectious diseases, the main causative organisms were Mycobacterium tuberculosis (14.9%), HIV (7.1%), HBV (3.3%), and HCV (2.6%). Upper-lower airways represented the most involved organ system (45% of discharges), followed by the gastroenteric tract (16.4%), and skin-soft tissues (7.4%), while systemic infectious diseases accounted for 14.9% of episodes. Such disorders predominated (up to 90% of cases) among non-regular migrants during 1999-2000, while after 2002 an increase in infectious disorders was observed among patients from Eastern Europe. From a health care-social perspective, although a reduced incidence of infectious diseases did not occur, the possibility of attributing them to individuals of ascertained identity and housing makes it possible to trace index patients, and ultimately strive towards well-planned and effective therapeutic-preventive interventions.