We discuss semiparametric regression when only the ranks of responses are observed. The model is Yi = F (x ′ iβ0 + εi), where Yi is the unobserved response, F is a monotone increasing function, xi is a known p−vector of covariates, β0 is an unknown p-vector of interest, and εi is an error term independent of xi. We observe {(xi, Rn(Yi)) : i = 1, . . . , n}, where Rn is the ordinal rank function...