CISO-FM is a Canadian radio station, which broadcasts a modern rock format at 89.1 MHz in Orillia, Ontario.

[1] Owned by Bayshore Broadcasting, the station received CRTC approval on June 1, 2009.

[2][3] The station launched in late 2010 as an adult contemporary format branded as Sunshine 89.1.

On November 1, 2018, CISO-FM rebranded to 89.1 Max FM with a classic hits format playing the best of the 70's, 80's and 90's.

On May 17, 2019, the station changed its format to modern rock but retained its "Max FM" branding.