The Bessel type polynomials considered are orthogonal with respect to the weight function obtained from the (unknown) classical Bessel weight function on R by adding a scalar multiple of the Dirac delta function at 0. The Bessel type polynomials are expressed in terms of the classical Bessel polynomials and as a 3 F 1 hypergeometric series. A second order differential equation with polynomial coefficients for the Bessel type polynomials is given.