The men's decathlon event at the 1986 World Junior Championships in Athletics was held in Athens, Greece, at Olympic Stadium on 16 and 17 July. Senior implements (106.7 cm (3'6) hurdles, 7257g shot, 2 kg discus) were used.
| Gold | Petri Keskitalo | |
| Silver | Mike Smith | |
| Bronze | Nikolay Zajats |
16/17 July
| Rank | Name | Nationality | 100m | LJ | SP | HJ | 400m | 110m H | DT | PV | JT | 1500m | Points | Notes | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| align=left | align=left | | 10.93 (w: 0.9 m/s) | 7.40 | 13.98 | 1.97 | 50.00 | 15.02 (w: 0.8 m/s) | 35.52 | 4.70 | 56.52 | 4:54.34 | 7623 | ||||
| align=left | align=left | | 11.11 (w: 0.8 m/s) | 7.20 | 13.62 | 1.97 | 48.58 | 15.45 (w: 0.3 m/s) | 38.20 | 3.70 | 60.94 | 4:28.95 | 7523 | ||||
| align=left | align=left | 11.12 | 7.05 | 12.49 | 1.97 | 49.27 | 15.33 | 39.82 | 4.80 | 50.46 | 4:41.00 | 7509 | |||||
| 4 | align=left | align=left | 11.46 | 6.91 | 13.71 | 1.94 | 50.62 | 15.78 | 41.78 | 4.20 | 62.60 | 4:36.37 | 7411 | ||||
| 5 | align=left | align=left | 11.41 | 6.90 | 12.08 | 1.91 | 49.63 | 15.64 | 38.02 | 4.40 | 56.52 | 4:19.31 | 7358 | ||||
| 6 | align=left | align=left | 10.99 | 6.79 | 13.47 | 1.91 | 50.39 | 15.58 | 44.88 | 4.00 | 59.26 | 4:55.85 | 7316 | ||||
| 7 | align=left | align=left |  | 11.38 | 6.93 | 12.56 | 2.03 | 51.41 | 15.85 | 40.30 | 4.30 | 48.74 | 4:30.84 | 7229 | |||
| 8 | align=left | align=left |  | 11.46 | 7.06 | 12.13 | 1.91 | 49.62 | 15.77 | 32.74 | 4.80 | 49.16 | 4:28.51 | 7215 | |||
| 9 | align=left | align=left | | 11.35 | 6.61 | 12.49 | 1.94 | 52.41 | 15.38 | 38.82 | 4.50 | 62.12 | 4:48.23 | 7203 | |||
| 10 | align=left | align=left | 11.05 w (w: 3.7 m/s) | 7.22 | 15.15 | 1.94 | 50.19 | 15.16 (w: 0.4 m/s) | 36.48 | 3.70 | 50.66 | 4:42.66 | 7108 | ||||
| 11 | align=left | align=left |  | 11.30 | 7.04 | 12.74 | 1.79 | 50.67 | 15.04 | 38.30 | 4.00 | 53.48 | 4:39.16 | 7090 | |||
| 12 | align=left | align=left |  | 11.40 | 6.87 | 12.68 | 1.97 | 51.65 | 15.16 | 31.96 | 4.20 | 55.00 | 4:45.08 | 7039 | |||
| 13 | align=left | align=left |  | 11.49 | 6.25 | 12.70 | 1.85 | 50.35 | 15.78 | 36.38 | 4.50 | 56.60 | 4:35.82 | 7017 | |||
| 14 | align=left | align=left | | 11.45 | 7.10 | 11.55 | 1.91 | 50.19 | 15.15 | 35.28 | 3.80 | 49.80 | 4:29.19 | 7007 | |||
| 15 | align=left | align=left | 11.60 | 6.83 | 13.24 | 1.97 | 51.65 | 16.11 | 36.98 | 4.00 | 48.32 | 4:42.81 | 6871 | ||||
| 16 | align=left | align=left |  | 11.49 | 6.69 | 11.67 | 1.91 | 50.19 | 15.88 | 40.30 | 3.40 | 51.22 | 4:30.70 | 6832 | |||
| 17 | align=left | align=left | 11.18 | 6.33 | 13.26 | 1.85 | 49.71 | 16.66 | 39.86 | 3.60 | 52.84 | 4:37.00 | 6822 | ||||
| 18 | align=left | align=left |  | 11.70 | 6.49 | 12.90 | 1.97 | 52.08 | 16.14 | 42.30 | 3.80 | 50.40 | 4:47.36 | 6784 | |||
| 19 | align=left | align=left | 11.65 | 6.69 | 11.55 | 1.79 | 50.41 | 16.52 | 36.64 | 4.20 | 57.42 | 4:41.35 | 6772 | ||||
| 20 | align=left | align=left |  | 11.55 | 5.94 | 11.59 | 1.85 | 49.61 | 15.56 | 34.78 | 4.00 | 56.88 | 4:33.79 | 6659 | |||
| 21 | align=left | align=left | | 11.66 | 6.20 | 12.63 | 1.64 | 53.48 | 17.92 | 34.00 | DNS | 52.98 | 4:51.57 | 5527 | |||
| 22 | align=left | align=left |  | 12.48 | 6.22 | 6.78 | 1.68 | 53.14 | 18.07 | 23.28 | 3.90 | 34.66 | 4:29.07 | 5250 | |||
| 23 | align=left | align=left | 11.40 | 6.18 | 8.96 | 1.76 | 54.92 | 18.70 | 30.34 | 2.60 | 34.76 | 5:31.08 | 4973 | ||||
| align=left | align=left | 11.12 | 7.03 | 11.63 | 1.97 | DNS | DNS | DNS | DNS | DNS | DNS | DNF | |||||
| align=left | align=left | 11.09 | 6.29 | 11.35 | 1.85 | DNS | DNS | DNS | DNS | DNS | DNS | DNF | |||||
| align=left | align=left | 11.68 | 6.17 | 10.57 | 1.91 | DNS | DNS | DNS | DNS | DNS | DNS | DNF | |||||
| align=left | align=left |  | 10.96 | 6.54 | 12.09 | 1.64 | DNS | DNS | DNS | DNS | DNS | DNS | DNF | ||||
| align=left | align=left | 11.42 | 6.45 | 13.07 | DNS | DNS | DNS | DNS | DNS | DNS | DNS | DNF | |||||
| align=left | align=left | 11.95 | DNS | DNS | DNS | DNS | DNS | DNS | DNS | DNS | DNS | DNF |
According to an unofficial count, 29 athletes from 21 countries participated in the event.