Multiferroic properties of orthorhombic HoMnO 3 (Pbnm space group) are significantly modified by epitaxial compressive strain along the a-axis. We are able to focus on the effect of strain solely along the a-axis by using an YAlO 3 (010) substrate, which has only a small lattice mismatch with HoMnO 3 along the other in-plane direction (the c-axis). Multiferroic properties of strained and relaxed HoMnO 3 thin films are compared with those reported for bulk, and are found to differ widely. A relaxed film exhibits bulk-like properties such as a ferroelectric transition temperature of 25 K and an incommensurate antiferromagnetic order below 39 K, with an ordering wave vector of (0 q b 0) with q b ≈ 0.41 at 10 K. A strained film becomes ferroelectric already at 37.5 K and has an incommensurate magnetic order with q b ≈ 0.49 at 10 K.