In a retrospective study of 210 women whose deliveries took place at 2 hospitals, the relationship of minor and major perineal lacerations to 30 separate factors is analyzed. Third and fourth degree perineal lacerations are found to be strongly related to low parity, low age, use of forceps, and episiotomies, and weakly related to normal pre-pregnant weight, weight gain over 30 pounds, anemia, long second stage, and epidural and pudendal anesthesia. First and second degree lacerations related to greater age, multiparity, prepregnant obesity, low weight gain, short second stage, large infant weight, and absence of anesthesia, forceps, and episiotomies. Analysis of the interactions of related variables and a comprehensive review of the literature are presented.