In this experimental study, two conical and one cylindrical diesel injector nozzle orifice geometries were compared to each other. Contrary to earlier studies, the outlet diameter of the conical orifice was constant in all nozzles. The main objective of the present study was to examine the effects of conical nozzle orifice geometry on fundamental spray characteristics when the outlet diameter is constant and independent of conicality. The spray tip penetration, spray angle, and mass flow rate were investigated, analyzed, and compared to different nozzle orifice geometries. The literature review shows that while the influence of conical nozzle orifice geometry on spray characteristics has been examined in several studies, some contradictions could be identified from these studies. This suggests that the topic is not comprehensively understood. Experimental fuel spray measurements were performed with a laser based backlight imaging system in a pressurized injection test chamber at room temperature. The density of ambient gas was 36 kg/m(3), which corresponds to the density in real diesel engine conditions at the end of a compression stroke. A clear difference was not found when non-evaporative spray tip penetration was compared to different conical and cylindrical nozzle orifice geometries. This is inconsistent with earlier studies where spray tip penetration was studied. The spray angle was narrower with conical, rather than cylindrical, nozzle orifice geometry and the mass flow rate was notably higher with conical nozzle orifice geometry, which is consistent with earlier studies.