An investigation was made as to whether the sexual cycle and pregnancy can be determined by means of vaginal smear in chinchillas. This study represents the first attempt to record changes which occur in the pattern of exfoliated cells in chinchilla's vaginal smear during anoestrus, proestrus, oestrus, metoestrus and pregnancy. Fifteen female chinchillas aged from 8 months to 3 years and bred through harem breeding method were used. The major change during proestrus was an increase in the proportion of superficial cells, with a corresponding decrease in other cells. Goblet cells were observed in the smears prepared by strong aspiration during this cycle. Neutrophils, small and large intermediates and parabasal cells were not found in the smear during oestrus and the smear consisted of superficial cells only. In the proportion of neutrophils, small and large intermediates and parabasal cells increased during metoestrus. In addition, metoestrum and foam cells were found in this cycle. In anoestrus; superficial and parabasal cells were present in small numbers. Also small and large intermediate cells as well as neutrophils were present. Traces of foam and metoestrum cells were found. During pregnancy, neutrophils generally of medium density were present, parabasal; small and large intermediate cells were present at low or medium density, and superficial cells were only present in trace amounts.