In real experimental tokamaks the necessity for access space between toroidal field coils spoils the ideal axisymmetry of the configuration. The "ripple" in toroidal field strength (typically a few percent) causes non-symmetric trapping of particles; the resultant drift orbits generally lead to the wall. A criterion is given for the avoidance of this particle loss. The TORMAG computer program is used to calculate a sample coil systsm that preserves experimental access while also meeting the orbit criterion. In present-day tokamaks, the main effect of the excessive toroidal field ripple is the loss of multi-keV ions from the tail of the Maxwellian, an effect that is reflected in the vertical asymmetry of the charge-exchange neutral diagnostic data. In thermonuclear plasmas, loss due to non-axisymmetry becomes important even for bulk plasma ions. The loss problems for alpha particles and for energetic injected ions (if isotropic) are particularly serious.