The purpose of this study was to use acoustic analyses to describe speech outcomes over the course of 1 year after radial forearm free flap (RFFF) reconstruction of the tongue. Eighteen Canadian English-speaking females and males with reconstruction for oral cancer had speech samples recorded (pre-operative, and 1 month, 6 months, and 1 year post-operative). Acoustic characteristics of formants (F1, F2), fundamental frequency (F0), and duration of 699 vowel and diphthong tokens were analysed. Furthermore, the changes in size of the vowel space area were studied, as well as the effects of radiation therapy (RT) and inclusion of the floor of the mouth (FOM) in the reconstruction. RFFF reconstruction was found to affect several characteristics in males, and a minimal number of variables in females. General signs of reduced ability to articulate were not observed. RT and FOM had no differing effects compared to non-RT or non-FOM. There were individual differences between patients. (Contains 1 table and 1 figure.)