A randomized study compared the Novak and Pipelle endometrial biopsy instruments with respect to quality of the biopsy obtained and pain related to the procedure. Fifty-five subjects were randomized to one of two groups. Twenty-six women had a biopsy using the Pipelle, followed immediately by one using the Novak instrument; 29 had the procedures performed in the reverse sequence. After the procedures, each woman completed a pain questionnaire. Individual histology slides were reviewed in a blinded fashion. The two biopsies from each subject were paired, and a reviewer indicated the preferred type of biopsy. The scores were analyzed by nonparametric tests. The instruments yielded biopsies of similar quality (z = -0.18, P = .856). Pain scores were lower for the Pipelle (z = -3.40, P = .001). The pathologist showed no preference when choosing Novak or Pipelle slides (chi 2 = 2.08, P = .149). In our patient population, the Pipelle instrument was comparable to the Novak instrument in obtaining adequate tissue and was significantly less painful.