Recurrent infections are a frequent cause of medical visits. They can be due to a heterogeneous group of dysfunctions that increase the susceptibility to pathogenic and opportunistic microorganisms, such as immunological deficiencies. To define an opportune rational treatment and to guide the molecular diagnosis of primary immunodeficiency diseases, we establish a program for the phenotypic diagnosis of these illnesses in Antioquia, Colombia, including clinical and laboratory evaluations of patients who present recurrent infections with abnormal evolution. Between August 1, 1994 and July 31, 2002, phenotypic diagnosis of primary immunodeficiency was made in 98 patients. Similar to data reported in the literature, antibody deficiencies were the most frequent (40.8%), followed by combined deficiencies (21.4%). This phenotypic characterization has allowed for appropriate treatments for each patient and, in some cases, functional and molecular studies that can lead to a definite molecular diagnosis.