Background Biological samples tend to be low in intrinsic contrast to visible transmitted-light microscopy. The development of contrast-enhancing methods such as phase contrast during the 20th century allowed the investigation of highly transparent yet detail-rich specimens by exploiting differences in refractive index and optical path difference to produce interference between two beam paths emerging from the sample plane1. Phase contrast microscopy has gone on to become a ubiquitous technique in cell biology and physiology, yet the optical design has remained relatively unchanged over recent decades; consisting of a light source, collimating optics, phase annulus, and condenser producing a hollow cone of illumination which passes through the sample. On the detection side, phase contrast objective lenses introduce a complementary ring of phase-retarding and attenuating material to alter the phase relationship of the undeviated illumination with respect to light deviated by passage through the sample. By recombining these two beams onto the detector contrast is obtained by exploiting constructive and destructive interference on the basis of the phase shift induced in transiting the sample. Method Presented here is a modified version of Zernike phase contrast microscopy1, in which condenser optics are entirely dispensed with yielding a condenser-free yet highly effective method of obtaining phase contrast in visible light microscopy. A ring of light emitting diodes is positioned within the optical light-path such that observation of the back focal plane of the objective places this ring, observed at virtual “infinity” with respect to the objective focal length, in appropriate conjunction with the phase ring to produce phase contrast. Results It is demonstrated that true phase contrast is obtained, whose geometry can be arbitrarily manipulated to provide a range of working distances and form factors. LED-ring phase contrast is demonstrated at phase position L, 1, 2, 3 and 4 across a range of magnifications and numerical apertures up to 100x and 1.4NA. LED phase contrast illumination is further implemented in conjunction with scanning ion conductance microscopy (SICM) to image a range of cultured cell lines; including ARPE-19, 3T3 fibroblast, and Caco-2 cells. Conclusion Condenser-free phase contrast microscopy using LED rings has significant potential to benefit physiology and cell biology by providing for arbitrary working distances in illuminating optics. By eliminating the need for a condenser assembly a range of concurrent imaging and measurement techniques will be technically facilitated through the provision of extra room to work. In addition the compact, low power, and versatile nature of LED illumination will further lend itself to miniaturisation and modification of existing phase contrast microscopy schemas in the future.