In Polish orthography, sz represents a voiceless retroflex fricative /ʂ/. It usually corresponds to š or ш in other Slavic languages. It is usually approximated by English speakers with the "sh" sound^[1]: vi (and conversely, Polish speakers typically approximate the English digraph sh with the "sz" sound), although the two sounds are not completely identical.

Like other Polish digraphs, it is not considered a single letter for collation purposes.

sz should not be confused with ś (or s followed by i), termed "soft sh", a voiceless alveolo-palatal fricative /ɕ/.

obszar^ⓘ (area, territory)
płaszcz^ⓘ (coat, cloak)
Tomasz^ⓘ (Thomas)

Compare ś:
świeca^ⓘ (candle)
iść^ⓘ (to go)
sierpień^ⓘ (August)

In Kashubian, sz represents a voiceless postalveolar fricative /ʃ/, identical to the English "sh". It corresponds to the voiceless retroflex fricative /ʂ/ in Polish.

These examples are Kashubian words that use the letter sz, with the English translation following.

• szãtopiérz = bat
• szczawa = sorrel
• szczãka = jaw
• szczëka = pike (fish type)
• szerszéń = hornet

Sz is the thirty-second letter of the Hungarian alphabet. It represents /s/ and is called "esz" /ɛs/. Thus, names like Liszt are pronounced /list/ list.

In Hungarian, even if two characters are put together to make a different sound, they are considered one letter (a true digraph), and even acronyms keep the letter intact.

Hungarian usage of s and sz is almost the reverse of the Polish usage. In Hungarian, s represents /ʃ/ (a sound similar to /ʂ/). Therefore, the Hungarian capital of Budapest is natively pronounced (/ˈbudɒpɛʃt/), rhyming with standard English fleshed rather than pest.

There is also a zs in Hungarian, which is the last (forty-fourth) letter of the alphabet, following z.

These examples are Hungarian words that use the letter sz, with the English translation following:

• szabó = tailor
• szép = beautiful
• szikla = rock
• szőke = blonde
• szülő = parent
• szusi = sushi
• Olaszország = Italy
• Szudán = Sudan

In the Wade–Giles system of Romanization of Mandarin, ⟨sz⟩ is used to represent the syllabic /s/ with the "empty rime". See Wade–Giles → Empty rime.

In the unpublished romanisation scheme employed by the Hong Kong government, sz is sometimes used in combination with e to represent the syllable /siː/, as in Sheung Sze Wan /sœːŋ˥.siː˥.waːn˥/ (Sēungsīwāan in Yale romanization).

Sz also appears in the sequence tsz, representing the syllables /t͡siː/ and /t͡sʰiː/, as in Tsz Tin Tsuen /t͡siː˧˥.tʰiːn˨˩.t͡sʰyːn˥/ and Tsz Wan Shan /t͡sʰiː˨˩.wɐn˨˩.saːn˥/ (Jítìhnchyūn and Chìhwàhnsāan respectively in Yale romanization).

• Hungarian alphabet
• Polish alphabet
• ß, called S-Sharp