The possibility of laser induced variation of optical and electrical properties of conductive nanocrystalline diamond (CNCD) films has been demonstrated. The films were produced by microwave plasma chemical vapor de-position (MPCVD) from CH 4 :H 2 :N 2 gas mixtures. The films were irradiated in air with 20 ns pulses of an ArF excimer laser (λ = 193 nm). It was found that low laser pulse intensity (~0.05 J/cm 2), well below film surface graphitization (~0.3 J/cm 2) and nanoablation (~0.08 J/cm 2) thresholds, induces changes of the film properties. The effect requires multiple pulsed irradiation and results in a decrease of the film electrical conductivity, which is accompanied by optical bleaching of the diamond film absorption.