A general product construction for perfect single-error-correcting codes over an arbitrary alphabet is presented. Given perfect single-error-correcting codes of lengths

, and

over an alphabet of order

, one can construct perfect single-error-correcting codes of length

over the same alphabet. Moreover, if there exists a perfect single-error-correcting code of length

over an alphabet of order

, then there exist perfect single-error-correcting codes of length

,

, and

, an integer). Finally, connections between projective planes of order

and perfect codes of length

over an alphabet of order

are discussed.