Sufficient　conditions　are　obtained　for　the　permanence　of　the　following　integrodifferential　model　of　mutualism　dN(1)(t)/dt　=　r(1)(t)N-1(t)　[K-1(t)　+　alpha(1)(t)　integral(infinity)(0)　J(2)(s)N-2(t　-　s)ds/1　+　integral(infinity)(0)　J(2)(s)N-2(t　-s)ds　-　N-1(t　-　sigma(1)(t))],　dN(2)(t)/dt　=　r(2)(t)N-2(t)　[K-2(t)　+　alpha(2)(t)　integral(infinity)(0)　J(1)(.)(s)N-1(t　-　s)ds/1　+　integral(infinity)(0)　J(1)(s)N-1(t　-　s)ds　-　N-2(t　-　sigma(2)(t))],　where　r(i),　K-i,　alpha(i)　and　sigma(i),　i　=　1,　2　are　continuous　functions　bounded　above　and　below　by　positive　constants.　alpha(i)　＞　K-i,　i　=　1,　2.　J(i)　is　an　element　of　C([0,　+　infinity),　[0,　+　infinity))　and　integral(infinity)(0)　J(i)(s)ds　=　1,　i　=　1,　2.　(c)　2006　Elsevier　Inc.　All　rights　reserved.