Instructions and logic provide vector horizontal compare functionality. Some embodiments, responsive to an instruction specifying: a destination operand, a size of the vector elements, a source operand, and a mask corresponding to a portion of the vector element data fields in the source operand; read values from data fields of the specified size in the source operand, corresponding to the mask and compare the values for equality. In some embodiments, responsive to a detection of inequality, a trap may be taken. In some alternative embodiments, a flag may be set. In other alternative embodiments, a mask field may be set to a masked state for the corresponding unequal value(s). In some embodiments, responsive to all unmasked data fields of the source operand being equal to a particular value, that value may be broadcast to all data fields of the specified size in the destination operand.