To evaluate the combined effect of endometrial thickness and pattern on clinical outcomes in females following in vitro fertilization/intracytoplasmic sperm injection and frozen-thawed embryo transfer (IVF/ICSI-FET). FET cycles using at least 1 morphological good-quality blastocyst conducted between 2012 and 2013 at a university-based reproductive center were reviewed retrospectively. Endometrial ultrasonographic characteristics were recorded on the day of progesterone supplementation in FET cycles. In the combined analysis, endometrial thickness groups (group 1: equal or < 8mm; group 2: >8mm) were subdivided into 2 endometrial patterns (pattern A: triple-line; pattern B: no-triple line). Clinical pregnancy rate, spontaneous abortion rate, and live birth rate in different groups were analyzed. A total of 1512 cycles were reviewed. The results showed that significant differences in endometrial thickness and pattern were observed between the pregnant group (n=1009) and no pregnant group (n=503) (P<.05), while no significant differences were found between the live birth group (n=844) and no live birth group (n=668). Combined analysis revealed those with endometrial thickness > 8mm and triple-line endometrial pattern had significant higher clinical pregnancy rates, while spontaneous abortion rates and live birth rates showed no significant differences among these subgroups. This study suggested neither individual nor combined analysis of endometrial thickness and pattern had predicting effects on live birth following IVF treatments, and embryo quality might be the one that really has effects.