In this paper we present results from the study on optical signal regeneration by using Mamyshev type regenerator and its dependence on fiber dispersion. Research is performed using computer simulation software Synopsis OptSim 5.3. Setup of investigated regenerator con- sists of a high power erbium doped fiber amplifier, highly nonlinear fiber and an optical bandpass filter that is slightly shifted away from the signal central frequency. Signal used for regenera- tion was an on-off keying return-to-zero code manipulated 40 Gbit/s pulse sequence covered with white noise. The regenerator performance was evaluated by obtaining the regenerated optical signal bit error ratio for different optical filters and fiber dispersion coefficients.