Early pregnancy loss (EPL) significantly reduces the initial success rate of assisted reproduction treatments and increases the psychological burden on the patient. The aim of the current study was to investigate the association between embryo quality and EPL in IVF. A retrospective study of 1471 women undergoing IVF between July 2000 and October 2004 was performed. Multivariate logistic regression models evaluated the effect on EPL of the woman's age, type and cause of infertility, endometrial thickness on the day of oocyte retrieval, performance of intracytoplasmic sperm injection, number of transferred embryos, embryo quality as assessed by the number of blastomeres in the leading transferred embryo at day 3, and the percentage of fragmentation. The 2902 oocyte retrieval-embryo transfer cycles resulted in 816 pregnancies (28.1%; 705 women) constituting the study cohort. Of these, 259 pregnancies (31.7%) ended in EPL and 557 (68.3%) in ongoing pregnancies. EPL risk was significantly associated with advanced (>35 years) maternal age (OR=1.53; 95% CI 1.12-2.09) and five or fewer blastomeres in the leading embryo transferred at day 3 (OR=1.82; 95% CI 1.16-2.85). In conclusion, the quality of transferred embryos, as assessed by the total number of blastomeres in the leading transferred embryo, and maternal age are predictors of EPL.