X-ray free electron lasers (XFELs) have delivered a billion fold increase in peak X-ray brilliance over conventional synchrotron radiation sources. These sources create new possibilities for structural studies of biological objects that go beyond what is possible with synchrotron radiation. Serial femtosecond crystallography is an XFEL method that allows high-resolution structures to be solved from micro-meter sized crystals, whereas single particle coherent X-ray imaging requires development to extend the resolution beyond a few tens of nanometres. Here we describe an intermediate approach: the XFEL imaging of biological assemblies with helical (1D translational) symmetry. We collected X-ray scattering images from samples of microtubules injected across an XFEL beam using a liquid microjet, sorted these images into class averages, merged these data into a 2D diffraction pattern extending to 2 nm resolution, and reconstructed these data into a projection image of the microtubule. Details such as the 4 nm monomer within the microtubule became visible in this reconstruction. These results illustrate the potential of single-molecule X-ray imaging of biological assembles with helical symmetry at room temperature.