Tooth preparation is a procedure done for replacements of missing teeth, where it not only reduces the tooth structure but also preserves the biological value of the tooth. These are carried out for Fixed Partial Dentures and Full Mouth Rehabilitation. Fixed partial dentures are commonly done in cases of single missing tooth as it mainly depends upon the span length and the abutment health. The abutment teeth play a main role in partial dentures where replacements depend upon the abutment health. The aim of this cross sectional study was to determine the prevalence of errors in tooth preparation. The sample size of this study was 200 subjects. This study is conducted in a university setting, Chennai. Data was collected from a digital case sheet record of 200 subjects and coding was done in MS Excel sheets and statistically analysed using IBM SPSS Version 20.0. Chi square tests were used to analyse the data statistically. These data were then graphically represented. In this study, prevalence of various errors in tooth preparation were noticed, among which over reduction (67.5%), under reduction (93%) and gingival damage (75%) were more prevalent among other errors in tooth preparation. Damage is mostly seen on the posterior regions especially in the mandibular distal aspects. To prevent these errors, low speed handpieces and proper equipment with utmost care should be provided. Therefore in conclusion, tooth preparation can lead to various errors and care has to be taken while doing tooth preparation.