Plasma activated mist (PAMI) is generated by tiny water vapor droplets passing through cold atmospheric plasma discharge. The effect of PAMI is compared to direct plasma exposure during treatment of breast cancer cells MCF-7. The direct plasma jet is operated with argon gas while the PAMI discharge is operated through ambient air and flowing mist. Both discharges are directed to cultured cells. Plasma is generated by an ac signal in KHz range. Mist with water droplets of 30 μm in diameter with addition of few drops of hydrogen peroxide is generated by an ultrasonic nebulizer. Cell viability and reactive oxygen species production are measured under argon plasma and PAMI in adherent treated cultured MCF-7 cells. After few minutes treatment time, percentage of viable cells goes down while percentage of apoptotic cells increases. This phenomena is enhanced with the application of indirect PAMI compared to direct argon plasma.