Abstract The spacial resolution in a streamer chamber is investigated as a function of the gas pressure in the chamber. For this purpose a small streamer chamber with a track sensitive volume of 50 mm diameter and 23 mm gap has been constructed and operated between 5 and 20 atm pressure. In this pressure range streamer densities from 43 to 67 streamers per centimeter were found. The track width 2 σ is mainly determined by the diffusion of the electrons and shrinks proportionally to 1 p . In addition, the influence of a magnetic field of 1.8 T on the diffusion was studied. At 20 atm one reaches a σ of 70 μm in space, which allows a measurement of charmed particle lifetimes as short as 10 −13 s.