| Competition: | Segunda División de México |
| Season: | 1965–66 |
| Winners: | Nuevo León (1st Title) |
| Matches: | 241 |
| Total Goals: | 801 |
| Prevseason: | 1964–65 |
| Nextseason: | 1966–67 |
The 1965–66 Mexican Segunda División was the 16th season of the Mexican Segunda División. The season started on 29 May 1965 and concluded on 19 December 1965. It was won by Nuevo León, for the first time, the champion was defined in a tiebreaker match, in which Nuevo León defeated Tampico with a score of 2-1.[1]
| Club | City | Stadium | |
|---|---|---|---|
| Celaya | Celaya | Estadio Miguel Alemán Valdés | |
| La Piedad | La Piedad | Estadio Juan N. López | |
| Laguna | Torreón | Estadio San Isidro | |
| Nacional | Guadalajara | Estadio Jalisco | |
| Nuevo León | Monterrey | Estadio Tecnológico | |
| Orizaba | Orizaba | Estadio Socum | |
| Pachuca | Pachuca | Estadio Revolución Mexicana | |
| Poza Rica | Poza Rica | Parque Jaime J. Merino | |
| Puebla | Puebla | Estadio Olímpico Ignacio Zaragoza | |
| Salamanca | Salamanca | Estadio El Molinito | |
| Tampico | Tampico | Estadio Tampico | |
| Tepic | Tepic | Estadio Nicolás Álvarez Ortega | |
| Texcoco | Texcoco | Estadio Municipal de Texcoco | |
| Torreón | Torreón | Estadio Revolución | |
| Ciudad Victoria | Ciudad Victoria | Estadio Marte R. Gómez | |
| Zamora | Zamora | Estadio Moctezuma |
Due to the tie on points between Tampico and Nuevo León it was necessary to hold a tiebreaker match at a neutral venue. This was held on 26 December 1965 at the Estadio La Martinica, León.