¶1*1195Storment, Stegmeyer & Read, Dennis Moore, St. Louis, Mo., for appellant; Paul M. Storment, Jr., St. Louis, Mo., of counsel.
¶2Robert D. Kingsland, U. S. Atty., Edward L. Dowd, Jr., Asst. U. S. Atty., St. Louis, Mo., for appellee.
¶3Before BRIGHT, STEPHENSON and McMILLIAN, Circuit Judges.
¶5Dennis Moore appeals from a judgment entered in the District Court for the Eastern District of Missouri1 upon a jury verdict finding him guilty of distribution of cocaine, 21 U.S.C. § 841(a)(1), and conspiracy to distribute cocaine, 21 U.S.C. §§ 841(a)(1), 846. Appellant was sentenced to six years imprisonment on each count, to be served concurrently. For reversal appellant argues the district court erred in (1) refusing to delineate its reasons for rejecting the. plea agreement, and (2) failing to grant appellant’s motion for judgment of acquittal on the conspiracy count. For the reasons discussed below, we affirm the judgment of the district court.
¶6On May 21, 1980, Dennis Moore was charged in a two-count indictment with (1) knowingly and intentionally distributing co*1196caine and (2) conspiring to distribute cocaine. Pursuant to Fed.R.Crim.P. 11, defense counsel and the assistant U.S. attorney met before trial and entered into an agreement whereby appellant would plead guilty to a charge of unlawful use of communications (telephone) in violation of 21 U.S.C. § 843(b) in exchange for dismissal of the original indictment. The district court refused to accept the guilty plea and gave no reasons on the record for refusal. The district court also did not conduct a voir dire of appellant before or after rejecting the agreement.
¶7Under Fed.R.Crim.P. 11,2 the district court need not accept every guilty plea; a district court is under no duty to consider a negotiated plea agreement. In re Yielding, 599 F.2d 251 (8th Cir. 1979). Rule 11 does not require district courts to either accept a guilty plea or delineate its reasons for rejecting it.3 Furthermore, although voir dire would not have been unreasonable,4 Rule 11 does not mandate such a procedure when the guilty plea has been rejected.
¶8In sum, it is held that the district court’s rejection of the proposed guilty plea was not beyond the scope of its broad discretion.
¶9Next, appellant argues that the district court erred in denying his motion for the judgment of acquittal on the grounds that insufficient evidence existed in the record to sustain a jury verdict of conspiracy to distribute cocaine. Irizarry v. United States, 508 F.2d 960 (2d Cir. 1974). The prosecution argues that the existence of a conspiracy rests in the purview of the jury as a finding of fact. See Hamling v. United States, 418 U.S. 87, 94 S.Ct. 2887, 41 L.Ed.2d 590 (1974).
¶10After carefully reviewing the record, we find that the evidence clearly establishes the existence of a conspiracy beyond a reasonable doubt. Appellant was present at the scene of the crime and admitted that he delivered the contraband as requested in furtherance of the transaction. Appellant discussed the transaction with his co-defendants prior to the distribution and admitted at trial that he “assumed that the substance he delivered was cocaine.” Willfulness, intent and guilty knowledge may be proved by circumstantial evidence and frequently cannot be proved in any other manner. United States v. Wisdom, 534 F.2d 1306 (8th Cir. 1976); see also United *1197States v. Edwards, 488 F.2d 1154 (5th Cir. 1974).
¶11Accordingly, the judgment of the district court is affirmed.