Extrachromosomal circular DNA complexes from erythrocytes and splenocytes isolated from Carassius carassius were examined by mica-press-absorption method. The method was described that released small polydisperse circular DNA molecules in situ from the erythrocytes and the splenocytes and that allows selective observation of the small circular DNA complexes bound to cellular components. The released polydisperse circular DNA complexes were absorbed preferentially on mica in a divalent cation-free medium then processed for electron microscopy. Small circular DNAs showed a heterogeneous size distribution of $2{sim}10{mu}m$ with a mean contour length of $4.3{mu}m$ for the circulating erythrocytes and that of $0.7{sim}3.6{mu}m$ with a mean contour of length $2.04{mu}m$ for the splencytes. Cells contained $100{sim}300$ copies and $300{sim}700$ copies obtained from the erythrocytes and the splenocytes, repectively. Possible biological functional implications for size distribution of extrachromosomal circular DNAs are discussed.