Italian Phrase
Non aprire mai la porta agli sconosciuti.
Meaning
Literally, ‘Never open the door to strangers.’ It is a strong safety warning, often used by parents or security personnel to stress that unknown people should not be let inside.
When to use
Use this phrase when giving a firm safety instruction, especially to children, guests, or anyone who might be tempted to open the door for an unknown visitor.
✦Grammar Breakdown
Nonapriremailaportaaglisconosciuti
Negative Imperative
The verb ‘aprire’ is placed in its infinitive form after ‘non’ to give a negative command (don’t open).
Adverb Placement
‘Mai’ (never) follows the verb in negative imperatives, reinforcing the prohibition.
Preposition + Article Contraction
‘a’ + ‘gli’ contracts to ‘agli’; it is used before masculine plural nouns like ‘sconosciuti’.
Gender & Number Agreement
‘Sconosciuti’ is masculine plural; if you want a mixed or feminine group, the same form is used in Italian.
🗨In Conversation
Non aprire mai la porta agli sconosciuti.
Never open the door to strangers.
Perché? Non è pericoloso?
Why? Isn't it dangerous?
✕Common Mistakes
Non aprire mai la porta a gli sconosciuti.
‘a gli’ should be contracted to ‘agli’; writing them separately is incorrect.
Non apri mai la porta agli sconosciuti.
Using the present indicative ‘non apri’ changes the meaning to ‘you never open’; the correct negative command uses the infinitive after ‘non’.
Non aprire mai la porta agli sconosciuta.
‘Sconosciuta’ is feminine singular; the noun ‘sconosciuti’ must agree with the plural ‘porta’ context.
↔Alternatives
Non aprire la porta a persone sconosciute.
Don't open the door to unknown people.
Mai aprire la porta a chi non conosci.
Never open the door to someone you don't know.
Non far entrare sconosciuti.
Don't let strangers in.
Cultural Tip
In Italy, especially in smaller towns, it’s common for families to stress this rule to children because doorbells are often used by salespeople or prank callers. The phrase is informal; in a formal safety briefing you might say ‘Si prega di non aprire la porta a persone sconosciute.’ The word ‘sconosciuti’ stays masculine plural even if the group includes women, which is typical in Italian gender conventions.