The Internalized Homonegativity Scale (IHN), created by Currie, Cunningham and Findlay, stands out among the instruments for assessing rejection toward homosexuality in non-heterosexual persons. In Mexico, Moral and Valle used the concept of internalized homonegativity in a broad sense to refer to fear and refusal to be misidentified and treated as a homosexual person regardless of one's sexual orientation. These Mexican authors applied an enlarged version of the IHN scale to a sample of health sciences students and, after performing several analyses, 16 items were selected. The aims of this research were to test the discriminability and internal consistency of the items composing the IHN-16 scale, calculate the internal consistency of the scale and its factors, contrast and compare the models of one and three factors proposed for the IHN-16 scale, test for factorial invariance of the IHN-16 scale across both sexes, verify the criterion validity of IHN-16 scale, and determine if social desirability introduces bias in the responses to the IHN-16 scale. The IHN-16 scale, the scale of Attitudes Toward Lesbian and Gay Men (ATLG), the scale of Subtle and Manifest Prejudice Toward Homosexual Persons (SMPTHP), and the Balanced Inventory of Desirable Responding (BIDR) were applied to a non-probability convenience sample composed of 202 medical students (48.5% women and 47% men). The 16 items comprising the IHN- 16 scale showed good properties of discriminability and internal consistency. The values of internal consistency of the IHN-16 scale and one of its three factors were high, and those ones of the other two factors were acceptable. The hierarchical model composed of three lower-order factors and one higher-order factor showed better properties of goodness of fit and invariance across sexes than the one-factor model; these properties improved after removing the items 2 and 12. The IHN-16 scale showed evidence of criterion validity, using as criterion variables the ATLG scale and the SMPTHP scale. The correlation between total scores of IHN-16 scale and BIDR was low, and the total score of IHN-16 scale was independent from the two factors of the BIDR. We concluded that IHN-16 scale is reliable and valid, and improves with the removal of items 2 and 12. The hierarchical model is not strictly invariant across women and men, but it is valid for both sexes. The use of the IHN-14 scale does not require statistical control of social desirability. For future studies, we proposed five new items to define a fourth factor of internal homonegativity named "fear of being seen as gay."
