Reinov O.I. On factorization of operators through the spaces l^p. Abstract: We give conditions on a pair of Banach spaces X and Y, under which (*) each operator from X to Y, whose second adjoint factors compactly through the space l^p, 1\le p\le+\infty, itself compactly factors through l^p. The conditions are as follows: either the space X*, or the space Y*** possesses the Grothendieck approximation property. The corresponding question for parameters p>1, p\neq 2, still being open, we show that for p=1 the conditions are essential: there exist Banach spaces with the bases for which the assertion (*) invalid for the case of l^1-factoring operators. 2. AMS Subject Classification: 47B10. Hilbert--Schmidt operators, trace class operators, nuclear operators, p-summing operators, etc. E-mail: orein@orein.usr.pu.ru Comments: TeX: AMSTeX. Russian (8 pp.)