Аннотация:A problem of existence of the hamiltonian cycles (h.c.) in toric lattice or, more precisely, in Tm,n = Jm × Jn graph with Jk as the k - apical oriented cycle is considered. By this means Tm,n is the oriented 'lattice' on tore with mn apexes and 2 mn edges. The condition for existence of h.c. in Tm,n graph consists in solvability of the system of equations in natural numbers. The system of equations is investigated with the help of the circular Hardy-Littelwood method. The some values for Jm,n-function, namely, numbers of system solving are obtained.