Abstract: The improved in-line air filter apparatus of the present invention includes an air filter housing disposed in-line on the engine air intake hose of an internal combustion engine, with a tubular air filter element longitudinally disposed therein and having a closed axial end of such tubular air filter element disposed upstream of an open axial downstream end, with the open tubular end having a size and shape substantially congruent with the size and shape of the engine air intake hose of the internal combustion engine for minimizing the turbulence of the filtered air supplied thereto, and with the closed upstream tubular end having an annular shaped air inlet portion surrounding such closed upstream tubular end for directing air longitudinally and inwardly through the body of the tubular air filter element.