The band structures of the doubly-odd 138Pm nucleus have been investigated using the 115In(28Si, 2p3n) 138Pm reaction at a beam energy of 145 MeV. The three previously known rotational bands viz., (i) the yrast one based on the πh11/2 ⊗ vνh11/2 configuration, (ii) a ΔI = 2 band with πh11/2 ⊗ ν1/2+ configuration at lower frequency but with a change in the neutron configuration to ν1/2+ at higher frequency, and (iii) one consisting of stretched E2 cascades at lower frequency but of dipole transitions after backbend and with suggested configuration of π5/2+ ⊗ νh11/2 have been modified and extended to higher spins. Two new bands have been identified. Of these, one consists of only quadrupole transitions, similar to that observed in band (iii), mentioned above, while the other consists of dipole transitions. The observed level properties have been compared to theoretical calculations performed within the Particle Rotor Model (PRM) with axial core and cranked shell model. The experimental branching ratios and B(M1)/B(E2) ratios of the transitions in the yrast band are well reproduced by PRM, assuming an axial prolate core. © 1998 Elsevier Science B.V.