increase it ?
there is a setting in the configuration of dosbox

Thanks, but if I play on full screen the sensitivity is still same.

MadMonk wrote:

Playing Doom, Doom II, Heretic, etc. the mouse sensitivity is very low. I use DOSBox v. 0.73 Could anyone help?

In dosbox.conf you can set the mouse sensitivity using these settings under the SDL section

Dosbox Wiki wrote:

sensitivity = 1..1000 Mouse sensitivity. Default is 100. (since 0.??) […]
Show full quote

sensitivity = 1..1000
Mouse sensitivity.
Default is 100.
(since 0.??)

Source

Additionally, why not just increase the mouse sensitivity in the game:

I increased the game's mouse sensitivity too but it's still quite low on full screen mode.

Maybe this is related? Mouse sensitivity changes between windowed and fullscreen

I've downloaded accidentally more DOSBox'es (when I got v. 73) like one and used the ''right'' one. Now I got the sensitivity higher.