Background: lmmunosuppressive therapy (1ST) with anti-T lymphocyte globulin (ATG) plus cyclosporine (CSA) is standard therapy in patients with non-severe @plastic anemia (AA) in need of treatment and severe aplastic anemia (SAA) who do not have an available HLA-matched donor. The aim of this study was to analyze patients submitted to different ATG preparations as first-line treatment. Patients and methods: We retrospectively analyzed adult aplastic anemia (AA) patients who received ATG as first-line treatment between 1999 and 2013 to compare hematologic response and survival. Results: During the time period mentioned 4 different ATG preparations had been used in 38 AA patients (34 severe, 4 non-severe). Responses were better with Lymphoglobulin (6 complete response 1 partial response, 0 refractory disease and 2 death within 3 months after ATG, i.e. during induction), Thymoglobulin (3, 1, 4 and 1, respectively) or ATGAM (1, 2, 1 and 1) compared to the ATG-Fresenius (ATG-F) group (3, 0, 6 and 6) (P =.07). Statistically significant inferior results with ATG-Fresenius (3 complete or partial responses, 6 refractoriness and 6 induction deaths) were evident when other preparations are lumped together (14 complete or partial responses, 5 refractoriness and 4 induction mortalities) (P =.045). Estimated 1 year survival rates were 52.5% versus 76.9%, respectively (P =.13). Conclusions: These data support the notion that not all ATG preparations are suitable for use in AA.