Sirna

Sirna may refer to:
 * Sírna, legendary High King of Ireland
 * Șirna, a commune in Prahova County, Romania
 * Sirna, Iran, a village in Markazi Province, Iran
 * Small interfering RNA (siRNA)
 * Syrna, also spelled Sirna, Greek village
 * Syrna (island), also spelled Sirna, Greek island
 * Sirna Therapeutics