The 1969 series 50 pesos banknote is no longer legal tender. It was demonetized on December 31, 1992, along with all pre-1993 paper notes, when Mexico revalued its currency (1 new peso = 1,000 old pesos) and later introduced polymer notes.
As a collectible, its worth depends on:
Typical retail range for uncirculated examples: $5–$20 USD. Circulated notes are worth less ($1–$5). Rare varieties or errors could fetch more.
Consult a reputable numismatic dealer or use platforms like eBay (sold listings), Numista, or PMG/PCGS grading services for accurate valuation.