RESULTS: 199 patients with ILD were in total evaluated. From them, 88 were included in one of following categories: 43 IPF and 45 CTD-ILD. The age of presentation was higher in patients with IPF (70.32 vs 62.35 for CTD-ILD; p 0.0010) and there was a predominance of woman in the CTD-ILD group (77.77% vs 41.83% for IPF; p 0.0013). Both, the percentage of FVC and DLCO, were higher in the group of CTD-ILD than IPF (75.95 % vs 64.17% for FVC; p 0.036 and 54.11% VS 39.73% for DLCO; p 0.0018). The presence of velcro rales in auscultation were observed in the totality of patients with IPF (100% vs 46.6% for CTD-ILD; p<0.001). Arthralgia, gastroesophageal reflux and Raynauds phenomenon were the symptom more frequent in CTD-ILD. The predominant auto-antibody in the CTD-ILD was antibody anti-nuclear (ANA) (48.8% vs 16.2% in IPF; p 0.002). The tomographic pattern more frequent in the CTD-ILD was NSIP pattern (35.55% vs 4.6% in IPF). Contrary, in IPF, the dominants patterns were definitive UIP, possible UIP and combinations of UIP and emphysema (83.7%, 11.6% and 32.5%). The fall of Delta FVC was higher for patients with IPF and in the subgroups analysis of CTD-ILD, there was a greater drop in FVC in patients with RA than in SS (Drop in Delta FCV in percentage 7.04% for IPF, 4.85% for RA and 0.28% for SSc; p 0.94).