An apparatus and method for performing a packed horizontal addition of words and doublewords. One embodiment of a processor includes a decoder to decode a packed horizontal add instruction which includes an opcode and one or more operands used to identify a plurality of packed words; a source register to store a plurality of packed words; execution circuitry to execute the decoded instruction, and a destination register to store a final result as a packed result word in a designated data element position. The execution circuitry includes operand selection circuitry to identify first and second packed words from the source register in accordance with the operands and opcode; adder circuitry to add the two packed words to generate a temporary sum; a temporary storage of at least 17 bits to store the temporary sum; and saturation circuitry to saturate the temporary sum if necessary to generate the final result.