1. The radii are obtained as 2 .4 and 1 .5 which corresponds to 4.1 pc and 2.2 pc, respectively, at a distance of the cluster for Ruprecht 25 and Czernik 6.
2. From the two-colour (U −B ) versus (B −V ) diagram, we esti- mated the interstellar reddening as E(B −V ) = 0 . 55 ±0 . 05 mag for Ruprecht 25 and 0.48 ±0.05 for Czernik 6.
3. Distances to the cluster Ruprecht 25 and Czernik 6 are esti- mated as 5.8 ±0.5 and 5.0 ±0.3 kpc, respectively. An age of 800 ±80 Myr and 40 ±10 Myr are determined for Ruprecht 25 and Czernik 6 respectively by comparing the isochrones of Z = 0 . 019 given by Girardi et al. (20 0 0) .
4. We have found mass-segregation effect with the confidence la- bel of 90% and 85% for the clusters Ruprecht 25 and Czernik 6 respectively. Present estimate of dynamical relaxation time in- dicates that both the clusters are dynamically relaxed. This may be due to star formation process or dynamical evolution of the clusters.