A theoretical study on the excited states of methylhypochlorite (CH3OCl) has been carried out using high level ab initio molecular orbital methods. The vertical excitation energies for the lowest two (1)A' states, three (1)A" states, three (3)A' states, and three (3)A" states are calculated using the multireference configuration interaction (MRCI) method with cc-pVTZ and cc-pVTZ+sp basis sets. In addition, the potential energy curves for the lowest eight states are examined along both the ClO and CO coordinates at the complete active space SCF (CASSCF) level of theory with cc-pVTZ basis set. Except for the ground state, all seven excited states are strongly repulsive along the ClO coordinate, which is in good agreement with recent experimental work. Two absorption bands with maximums at 235 nm and 308 nm in the experimental UV spectra of CH3OCl can be assigned to the transitions X (1)A' --> 1 (1)A" and X (1)A' --> 2 (1)A'.