A novel defected ground structure (DGS) feedline element with two transmission zeros and flat passband is proposed. The zeros can be tuned individually by the DGS geometry to improve the low order filter's selectivity. A traditional microstrip parallel coupled‐line bandpass filter cascading this new element, not only achieves the selectivity improvement, but also its basic design formulation is retained. A prototype DGS filter was designed and tested to validate its performance.