The aim of this cross-sectional retrospective study was to describe clinical and functional characteristics and the microbiological profile of an adult population with cystic fibrosis. The study was performed at the Pulmonary Diseases Service of the Hospital of the Medical School of the State University of Campinas. The charts of 54 adults (27 males, 27 females) with cystic fibrosis were reviewed. Demographic, clinical, and microbiological data were collected. Clinical and functional characteristics of patients with chronic Pseudomonas infection were compared with those without it. The mean age of the patients was 41.8 years and the mean sweat chloride concentration was 106.4 mEq/L. Forty-nine percent had chronic respiratory symptoms only after 18 years of age, and 85% reported chronic production of purulent sputum. Six percent had diarrhea or fat in stools, and no patient suffered from diabetes mellitus. Pseudomonas was present in 48%, and 73% of them had the mucoid strain. Others agents found were Staphylococcus aureus (28%), Hemophylus sp. (34%), Aspergillus sp. (22%), Stenotrophomonas maltophilia (9%), Acinetobacter sp. (7%), and Burkholderia cepacia (2%). Nontuberculous mycobacteria were found in sputum from 9 patients (11%); 34 patients (67%) had obstructive ventilatory defect; and 47% had obstruction and restriction. Concerning the groups with and without Pseudomonas colonization, only the values of sweat chloride were significantly higher in chronic colonized patients. Less severe phenotypes of cystic fibrosis may be found among patients previously diagnosed as having bronchiectasis. Chronic colonization with Pseudomonas aeruginosa in this study was not associated with worse clinical status but colonized patients did show significantly higher levels of chloride in sweat.