Traditionally, no — going “regimental” means wearing nothing underneath a kilt. In modern times, it’s entirely a personal choice. Most people today wear underwear such as briefs, boxer-briefs, or compression shorts for comfort, hygiene, sport, or modesty, and the right choice really depends on the occasion, the weather, and personal confidence.
Tradition vs. today
Historically, kilts were often worn without underwear, especially in military regiments and ceremonial Highland dress. That “regimental style” became part of Highland identity in its own right, tied to practicality, freedom of movement, and tradition all at once. Today, kilt-wearing is far more flexible — people choose whatever suits them based on comfort and setting, and most modern wearers lean toward boxer-briefs, compression shorts, or breathable underwear, especially for long events or anything involving active movement.
What to wear underneath, by occasion
For formal events — weddings, black tie, ceremonies — appearance and confidence matter most. Seamless briefs or fitted boxer-briefs avoid visible lines when sitting or dancing, and the outfit pairs naturally with a Prince Charlie jacket, dress sporran, and ghillie brogues for a complete formal look.
For Highland Games, dancing, and other active events, movement-heavy occasions call for more practical choices. Compression shorts or moisture-wicking boxer-briefs help prevent chafing, improve comfort, and keep everything supported during activity.
For casual wear and travel, comfort takes priority. Cotton or bamboo boxer-briefs work well for long hours, travel, or warm weather, since they’re breathable and soft against the skin.
For cold or windy weather, thermal base-layer shorts add warmth without changing the kilt’s traditional appearance, and they work well under heavier tartan fabric specifically.
Etiquette worth knowing
It’s considered impolite to ask someone what they wear under their kilt — that’s a genuine social rule, not just an old joke. When sitting, keep the front apron in place and maintain a neat posture, knees together or slightly angled. And make sure a kilt pin goes through the outer apron only, never both layers, to keep the structure and movement intact.
Fabric and fit tips
Choose breathable, moisture-wicking fabrics for comfort, and avoid thick seams that can show through lighter tartans. Mid-thigh boxer-briefs or short compression styles tend to work best with kilt length specifically. A well-fitted kilt worn at the natural waist also improves comfort and appearance more broadly, regardless of what’s worn underneath.
Women and children
Women can choose undergarments based on comfort and modesty, with seamless briefs or shorts being the common choice. For children, comfort and practicality come first — soft underwear or shorts work well for events or school functions.
Key styling foundations
A properly worn kilt sits at mid-knee length. The sporran hangs about 3–4 inches below the belt buckle. Ghillie brogues should be neatly laced, and kilt hose with flashes arranged cleanly to finish the look.
Bottom line
What you wear under a kilt comes down to personal choice. Tradition allows going regimental, while modern wearers often prefer underwear for comfort and practicality — either is fine. What actually matters is wearing the kilt correctly, confidently, and with some respect for the tradition behind it.
Whatever you choose to wear underneath, the kilt itself does most of the work for comfort and fit. If you’re after the classic all-day option, our utility kilts are built for movement. If you want something closer to military tradition, our tactical kilts are the modern take on regimental style.