In a woman with infertility and an endometrial polyp, we analyzed the nucleotide sequence of the beta-subunit of her luteinizing hormone which showed anomalous immunogenecity in that it was recognized by time resolved-fluoroimmunoassay but not by immunoradiometric assay. The sequence analysis showed two substitutional mutations of beta-subunit Trp (TGG) to Arg (CGG) and Ile (ATC) to Thr (ACC). The variant luteinizing hormone might have had some relation to the infertility and the endometrial polyp. been described [2, 4, 13-15]. Although the role of the variant LH is still unclear, it has different biologicl activity as compared to normal LH and may play a role in causing infertility, menstrual disorder, endometriosis and spontaneous miscarriage [1, 3, 4, 9, 10, 17]. We now report a study of the DNA sequence of beta-subunit of anomalous LH in an infertile patient with an endometrial polyp.