We show that a necessary and sufficient condition for the existence of a Kp ,2q factorization of the symmetric complete tripartite digraph K~1,n2,n3 is (i) ni = n2 = n3 == 0 (mod p) for p = q, (ii) ni = n2 = n3 == 0 (mod dp'q'(p' + 2q')) for p =Iq and p' odd, (iii) ni = n2 = n3 == 0 (mod dp'q'(p' + 2q')/2) for p =Iq and p' even, where d = (p, q), p' = p/d, q' = q/d.