OBJECTIVES: To compare the price changes of the essential and the non-essential anti-infective medicines in Tianjin, China using index method. METHODS: Data were extracted from inpatient claims in Urban Employee Basic Medical Insurance database of Tianjin, China, from 2006 to 2010. Price indices were measured by Fisher and chained Fisher index formulas by quarter. The quantity weight unit was defined daily dose (DDD) and the price unit was the price per DDD. Price indices were calculated both at molecule level (defined by active ingredient) and product level (defined by molecule, strength, preparation, and manufacturer). RESULTS: The data contained 41 molecules and 786 products among the essential anti-infective medicines, and 81 molecules and 636 products among the non-essential anti-infective medicines. For the essential anti-infective medicines, the price index decreased to 0.90 (in chained Fisher index at molecule level) from 2006 Q1 to 2010 Q4, and the price index for the non-essential anti-infective medicines decreased to 0.73 (in chained Fisher index at molecule level) during the same period. For the essential and non-essential anti-infective, the results of chained Fisher and unchained counterparts were similar (10% vs. 10% for the essential and 28% vs. 27% for the non-essential at molecule level). The price indices at molecule level decreased slower than the counterparts at product level (10% vs. 24% for the essential and 27% vs. 30% for the non-essential in chained Fisher index). CONCLUSIONS: The price of the essential and non-essential anti-infective medicines among national reimbursement drug list had decreased in Tianjin, China, but the price of the essential anti-infective medicines decreased slower than the non-essential anti-infective medicines.