Parametric equations of state near the critical point of fluids are discussed with emphasis on their physical implications and potential applications. Two specific phenomenological proposals in which the "distance" parameter is directly related to singular thermodynamic functions are studied. One of these is shown to be obtainable from a general equation of state in which the isothermal compressibility is used as a scaling factor. Both proposals are found to be in agreement with the PVT data on He4 and He3. Consistency checks between PVT and specific-heat data on these fluids are made using the parametric equations.