In this paper we obtain an analytic formula for the decay rate of semileptonic decays of baryons, without neglecting any form factor allowed by Lorentz covariance or the mass of the charged lepton. No assumption is made as to the smallness of the momentum transfer. Our result is appropriate for semileptonic decays of baryons containing charm, bottom, and top quarks. It can be very helpful in cross-checking decay-rate expressions obtained by numerical integration.