Abstract. This work describes the development of an automatic estimator of perceptual femininity (PF) of an input utterance using speaker verification techniques. The estimator was designed for its clinical use and the target speakers are Gender Identity Disorder (GID) clients, especially MtF (Male to Female) transsexuals. The voice therapy for MtFs, which is conducted by the second author, comprises three kinds of training; 1) raising the baseline F0 range, 2) changing the baseline voice quality, and 3) enhancing F0 dynamics to produce an exaggerated intonation pattern. The first two focus on static acoustic properties of speech and the voice quality is mainly controlled by size and shape of the articulators, which can be acoustically characterized by the spectral envelope. Gaussian Mixture Models (GMM) of F0 values and spectrums were built separately for biologically male speakers and female ones. Using the four models, PF was estimated automatically for each of 142 utterances of 1...