Exhibit 21

Subsidiaries of the Company

Set forth below is information concerning the Company's (MRG) subsidiaries and their respective ownership.

|Name                                          |  | Jurisdiction
and Form   |  | Percentage
of Ownership                 
|--------------------------------------------- |  | ----------------------- |  | ----------------------------------------
|Circus Circus Casinos, Inc.(1)                |  | Nevada corporation      |  | 100% MRG                                
|Slots-A-Fun, Inc.(2)                          |  | Nevada corporation      |  | 100% MRG                                
|Edgewater Hotel Corporation(3)                |  | Nevada corporation      |  | 100% MRG                                
|Colorado Belle Corp.(4)                       |  | Nevada corporation      |  | 100% MRG                                
|New Castle Corp.(5)                           |  | Nevada corporation      |  | 100% MRG                                
|Ramparts, Inc.(6)                             |  | Nevada corporation      |  | 100% MRG                                
|Circus Circus Mississippi, Inc.(7)            |  | Mississippi corporation |  | 100% MRG                                
|Mandalay Corp.(8)                             |  | Nevada corporation      |  | 100% MRG                                
|Mandalay Development                          |  | Nevada corporation      |  | 100% MRG                                
|Ramparts International ("RI")                 |  | Nevada corporation      |  | 100% MRG                                
|Galleon, Inc. ("GI")                          |  | Nevada corporation      |  | 100% MRG                                
|M.S.E. Investments, Incorporated ("MSE")      |  | Nevada corporation      |  | 100% MRG                                
|Last Chance Investments, Incorporated ("LCI") |  | Nevada corporation      |  | 100% MRG                                
|Goldstrike Investments, Incorporated ("GSI")  |  | Nevada corporation      |  | 100% MRG                                
|Diamond Gold, Inc. ("DGI")                    |  | Nevada corporation      |  | 100% MRG                                
|Oasis Development Company, Inc. ("ODC")       |  | Nevada corporation      |  | 100% MRG                                
|Circus Circus Michigan, Inc. ("CCM")          |  | Michigan corporation    |  | 100% MRG                                
|Railroad Pass Investment Group ("RPIG")(9)    |  | Nevada partnership      |  | 70% MSE
20% LCI
10% GSI                 
|Jean Development Company ("JDC")(10)          |  | Nevada partnership      |  | 40% MSE
40% LCI
20% GSI                 
|Jean Development West ("JDW")(11)             |  | Nevada partnership      |  | 40% MSE
40% LCI
12% GSI
8% DGI          
|Gold Strike Fuel Company                      |  | Nevada partnership      |  | 162/3% MSE
162/3% LCI
162/3% GSI
50% ODC
|Jean Fuel Company West                        |  | Nevada partnership      |  | 40% MSE
40% LCI
12% GSI
8% ODC          
|Nevada Landing Partnership ("NLP")            |  | Illinois partnership    |  | 40% MSE
40% LCI
5% GSI
15% DGI          
|Gold Strike L.V. ("GSLV")                     |  | Nevada partnership      |  | 52% MSE
39% LCI
6.5% GSI
2.5% DGI       

---

|Other Interests:                  |  |                                    |  |          
|--------------------------------- |  | ---------------------------------- |  | ---------
|Circus and Eldorado Joint Venture |  | Nevada partnership                 |  | 50% GI   
|Detroit Entertainment, L.L.C.     |  | Michigan limited liability company |  | 53.5% CCM
|Elgin Riverboat Resort            |  | Illinois partnership               |  | 50% NLP  
|Victoria Partners                 |  | Nevada partnership                 |  | 50% GSLV 

---

---

QuickLinks