Purpose: To evaluate the speech perception of adult hearing aid users pre and post fine tuning based on Speech Mapping in Brazilian Portuguese (SMBP). Methods: Twenty adults aged 18 to 60 years old presenting moderate to severe bilateral symmetrical sensorineural hearing loss and wearing digital hearing aids programmed according to the prescriptive formula National Acoustics Labs, Non-Linear, version 1 (NAL-NL1) for at least six months participated in this study. The test Lists of Sentences in Portuguese (LSP) has been used to evaluate speech perception. The test was applied in two different moments: T1 -before hearing aid fine tuning based on the SMBP and T2 -after fine tuning based on SMBP. The LSP test allowed the Sentence Recognition in Silence (SRTS) and in Noise (SRTN) Threshold calculation and the minimal signal to noise ratio (SNR) required to understand the sentences. Results: There was significant improvement of SRTS and SRTN in moment T2, or after hearing aid fine-tuning, to reach the prescribed targets. In both tests decreased values could be observed; the average SRTS fell from 39.60 dB to 34.41 dB and the signal to noise ratio (SNR) fell from 5.82 dB to 3.34 dB. Conclusion: It was possible to establish a clear link between achieving the prescribed targets and the improvement in speech perception. Hearing aid users performed better on speech perception tests after adjustments of the electroacoustic characteristics of their hearing aids based on the Speech Mapping procedure.