We prove theorems on interpolation of quasilinear operators of weak type (ϕ0, ψ0, ϕ0, ψ1) in Lorentz spaces. The operators under study are analogs of the Calderón operator and the Benett operator for concave and convex functions ϕ0( t), ψ0( t), ϕ1( t), and ψ1( t).