Objective. To determine the frequency and clinical and HLA associations of anticardiolipin (aCL) antibodies in patients with systemic lupus erythematosus (SLE), as well as their impact on survival. Methods. We studied 139 patients with SLE seen at a university based practice. We tested for clinical, laboratory, and HLA associations with levels of aCL antibody isotypes either in sera available in the bank (distant past) or in 2 samples. Demographic, clinical, laboratory, and HLA data were subjected to univariate survival analysis; variables of importance were entered into Cox multivariate regression analyses. Results. aCL antibodies (any isotype) were present in 57 (41.0%) of the 139 patients tested in the distant past sample, and in 23 (32.3%) as a persistent event in the 71 patient subgroup tested twice. IgG aCL were significantly associated with deep venous thrombosis (DVT) (p = 0.04). No other clinical or HLA association was found with aCL positivity. In the survival analyses, older age at diagnosis, presence of major infections, endstage renal disease, and IgM aCL antibody positivity in the distant past emerged as important independent factors adversely affecting survival. In the subgroup tested twice for aCL antibodies (n = 71), persistent IgM aCL antibody positivity (n = 10) emerged as an important independent factor. Among the subgroup of patients that had HLA data available (n = 88), HLA- DQw7 and thromboembolic events also adversely affected survival. Conclusion. We confirmed the association of IgG aCL antibody positivity with DVT, and the impact on survival of endstage renal disease, major infections, and older age at diagnosis. IgM aCL antibody positivity present either as an isolated event in the distant past or as a persistent finding, thromboembolic events, and HLA-DQw7 emerged as important prognostic factors.