The methylthio (CH3S) radical has been formed by KrF laser photolysis of dimethyl disulfide (CH3SSCH3) in a free-jet expansion. The Ã2A1←-X̃2E laser-induced fluorescence excitation spectrum was obtained in the wavelength region 350-382 nm. The origin lies at 26 526.3 cm-1 and the spin-orbital splitting for X̃ (2E 3/2 and 2E1/2) was determined to be -259.1 cm-1 Several progressions indicated that v′2 -1098 ±2, v′3 = 401 ± 2 cm-1 and (with less certainty) v′6 = 635 ±10 cm-1. The predissociation threshold was estimated to be slightly above 28 016 cm-1, ∼ 1490 cm-1 above the v′ = 0 level of the A state. The dispersed fluorescence was observed in the 363-530 nm region. The main progressions give v″2 = 1313 ±5 cm-1, v″3 = 727 ±3 cm-1, and v″5 = 1496 ± 6 cm-1. Weaker lines are also consistent with some possible vibrational frequencies v″1 = 2776 cm-1, v″4 = 2706 cm-1, and v″6 = 586 cm-1.