The objective of this study was to develop a reliable HAART optimism scale among HIV-positive women in Uganda and to test the scale's validity against measures of fertility intentions, sexual activity, and unprotected sexual intercourse. We used cross-sectional survey data of 540 women (18-50 years) attending Mbarara University's HIV clinic in Uganda. Women were asked how much they agreed or disagreed with 23 statements about HAART. Data were subjected to a principal components and factor analyses. Subsequently, we tested the association between the scale and fertility intentions and sexual behaviour using Wilcoxon rank sum test. Factor analysis yielded three factors, one of which was an eight-item HAART optimism scale with moderately high internal consistency (alpha = 0.70). Women who reported that they intended to have (more) children had significantly higher HAART optimism scores (median = 13.5 [IQR: 12-16]) than women who did not intend to have (more) children (median = 10.5 [IQR: 8-12]; P < 0.0001). Similarly, women who were sexually active and who reported practicing unprotected sexual intercourse had significantly higher HAART optimism scores than women who were sexually abstinent or who practiced protected sexual intercourse. Our reliable and valid scale, termed the Women's HAART Optimism Monitoring and EvaluatioN scale (WHOMEN's scale), may be valuable to broader studies investigating the role of HAART optimism on reproductive intentions and sexual behaviours of HIV-positive women in high HIV prevalence settings.