Tear chloride concentration was used as an indicator of hypotonic (reflex tear) response to contact lens presence in the eye. Individual responses to rigid and to hydrophilic lenses were thus monitored and quantitatively compared from the time of dispensing until full wearing time was achieved. Although the initial tear imbalances to hydrophilic lenses were somewhat less than those to rigid lenses, they were, nevertheless, detectable. Restoration to prefitting baseline levels was for the most part achieved within the first 5 days, and did generally parallel the reduction in subjective awareness experienced by the patient.