Despite the recent technological advances in in vitro fertilization and embryo transfer (IVF-ET), a significant proportion of women still do not become pregnant after long-term infertility, whether it is originally due to older age or other undetermined factors. In the present study, macrophage activating Chinese herbs (MACH) were evaluated for their effects on embryo qualities in women who were undergoing repeated IVF-ET because of long-term infertility. Thirty women, who had significantly low rates of developing good quality cleaved embryos and did not become pregnant after three or more cycles of Assisted Reproductive Technology (ART) procedure, were included in the study. Oral administration of MACH significantly increased the percentage of good quality early stage blastocysts (the number of grade 1 or grade 2 cleaved embryos/the number of retrieved oocytes) from 18.7 ± 16.2% to 36.1 ± 27.1% (1.9-fold increase, p < 0.01). The rate of good quality early stage blastocysts increased in all patients. In 19 patients who desired embryo transfer using late stage blastocysts, MACH significantly increased the percentage of late stage blastocysts from the initial value of 14.8 ± 11.2% to 21.1 ± 23.1% (1.4-fold increase, p < 0.05). The rate of embryonic progress into late stage blastocyst increased in 52.6% (10/19) of the patients. Furthermore, treatment with MACH significantly decreased the plasma follicle stimulating hormone (FSH) concentration on the day of oocyte retrieval from 14.4 ± 3.2 to 10.5 ± 2.4 mIU/ml (p < 0.05). No adverse events were observed with MACH supplementation, and there was no patient dropout. Administration of MACH resulted in improved embryo quality in the difficult cases. The present study demonstrates a new benefit of this herbal blend in women with refractory infertility of unknown etiology.