Single-chain miniantibodies (scFv's) to actin were obtained by the phage display method. A naive combinatorial phage display library of murine scFv's (containing 2•108independent recombinant clones) was used to select miniantibodies. After three rounds of selection two clones producing miniantibodies to chicken smooth muscle actin with affinity constants of 1.4•107and 1.2•106M-1were chosen. The isolated miniantibodies could specifically detect various plant and animal actins. © 2005 Pleiades Publishing, Inc.