Objective To investigate the effects of letrozole combined with human menopausal gonadotropin（HMG） on sex hormone levels and ovulation in patients with polycystic ovary syndrome（PCOS）. Methods A total of 76 patients with PCOS admitted to a hospital in Henan Province from August 2020 to August 2021 were selected as subjects

who were assigned to a control group and an experimental group using the random number table method

with 38 cases in each group. Patients in the control group received HMG therapy

and patients in the experimental group received letrozole in combination with HMG therapy. The ovulation rate and single follicle ovulation rate were compared between the two groups; the hormone levels

including follicle-stimulating hormone（FSH）

total testosterone（T）

estradiol（E2） and luteinizing hormone（LH）

were compared before and after the treatment. The endometrial thickness

ovulation number and mature follicle number were compared before and after the treatment; the pregnancy outcomes and the incidence of adverse drug reactions were compared between the two groups.Results The ovulation rate and single follicle ovulation rate in the study group were higher than those in the control group

and the differences were statistically significant（P<0.05）. No statistically significant difference in the levels of FSH

LH

E2 and T was observed between the 2 groups of patients before the treatment（P>0.05）. The levels of FSH

LH and E2 in the 2 groups after the treatment were higher than those before the treatment

with the experimental group higher than the control group

and the differences were statistically significant（P<0.05）. The T levels of patients in the 2 groups after the treatment were lower than those before the treatment

with the experimental group was lower than the control group

and the differences were statistically significant（P<0.05）. There was no statistically significant difference in the endometrial thickness

ovulation number and number of mature follicles before the treatment between the 2 groups（P>0.05）. The endometrial thickness in the 2 groups after the treatment was higher than that before treatment

with the experimental group higher than that in the control group

and the difference was statistically significant（P<0.05）. The number of ovulation and mature follicles in the 2 groups after treatment was higher than those before the treatment

with the experimental group higher than the control group

and the difference was statistically significant（P<0.05）. The pregnancy rate in the experimental group was higher than that in the control group

and the difference was statistically significant（P<0.05）. There was no statistically significant difference between the incidence of adverse drug reactions between the 2 groups（P>0.05）. Conclusion The clinical effects of letrozole combined with HMG in the treatment of PCOS is marked

which can improve the hormone level of patients

promote ovulation and follicle maturation and has high therapeutic value as a safe therapy. These benefits justify a wider application of this therapy clinically.