Aim: This study aimed to measure the effect of two different framework materials on speech. Materials and methods: Twenty participants with maxillary class IV arches (maxillary four anterior teeth missing) each patient received two prostheses alternating in a cross-over design. For both prostheses, CAD designed and printed resin patterns of the framework were made. For the Co-Cr metallic framework, the resin was then invested and cast conventionally. For the PEEK group, it was constructed by injection molded technique (for two press technique). Evaluation of speech was done on the same visit of prosthesis insertion, then patients were scheduled for one and three months follow-up visits for each prosthesis using a Computerized Speech Lab (CSL) (spectrogram). The Visual analog scale (VAS) was used to assess the level of patient satisfaction using a questionnaire three months after denture insertion. Results: For speech evaluation: the PEEK group showed higher statistical significance mean duration for all sounds compared to Co-Cr group after three months p≤0.05. Also PEEK showed lower frequency levels for all sounds p≤0.05 except (n,l) p > 0.05. For patient satisfaction: PEEK RPD recorded significantly higher satisfaction scores group as regard the esthetic appearance, comfort and overall general satisfaction compared to the Co-Cr RPD group but there were insignificant differences (P>0.05) between the two groups regarding retention, stability and masticatory function. Conclusion: Co-Cr RPDs showed better speech qualities compared to PEEK RPDs. Patients with PEEK frameworks were more satisfied regarding RDPs appearance, comfort and overall satisfaction than patients with metallic Co-Cr frameworks.