The Imperial Russian Army (Russian: Ру́сская импера́торская а́рмия, romanized: Rússkaya imperátorskaya ármiya) was the army of the Russian Empire, active from 1721 until the Russian Revolution of 1917. It was organized into a standing army and a state militia. The standing army consisted of regular troops and two forces that served on separate regulations: the Cossack troops and the Muslim troops.

A regular Russian army existed after the end of the Great Northern War in 1721. During his reign, Peter the Great accelerated the modernization of Russia's armed forces, including with a decree in 1699 that created the basis for recruiting soldiers, military regulations for the organization of the army in 1716, and creating the College of War in 1718 for the army administration. Starting in 1700 Peter began replacing the older Streltsy forces with new Western-style regiments organized on the basis of his already existing Guards regiments.

After the Napoleonic Wars the active Russian Army was maintained at just over 1 million men, which was increased to 1.7 million during the Crimean War. It remained at around this level until the outbreak of World War I, at which point Russia had the largest peacetime standing army in Europe, about 1.3 million. The wartime mobilization increased this to a strength of 4.5 million, and in total 15 million men served from 1914 to 1917.

In March [O.S. February] 1917 the Imperial Army swore loyalty to the Russian Provisional Government after the abdication of Emperor Nicholas II, though the official status of the monarchy was not resolved until September 1917, when the Russian Republic was declared. Even after the February Revolution, despite its ineffectiveness on the offensive, the majority of the army remained intact and the troops were still at the front lines. The "old army" did not begin disintegrating until early 1918.

Russian tsars before Peter the Great maintained professional hereditary musketeer corps known as streltsy. These were originally raised by Ivan the Terrible; originally an effective force, they had become highly unreliable and undisciplined. In times of war, the armed forces were augmented by peasants.

The regiments of the new order, or regiments of the foreign order (Полки нового строя or Полки иноземного строя, Polki novovo (inozemnovo) stroya), was the Russian term that was used to describe military units that were formed in the Tsardom of Russia in the 17th century according to the Western European military standards.

There were different kinds of regiments, such as the regulars (infantry), dragoons, and reiters. In 1631, the Russians created two regular regiments in Moscow. During the Smolensk War of 1632–1634, six more regular regiments, one reiter regiment, and a dragoon regiment were formed. Initially, they recruited children of the landless boyars and streltsy, volunteers, Cossacks and others. Commanding officers comprised mostly foreigners. After the war with Poland, all of the regiments were disbanded. During another Russo-Polish War, they were created again and became a principal force of the Russian Army. Often, regular and dragoon regiments were manned with datochniye lyudi for lifelong military service. Reiters were manned with small or landless gentry and boyars' children and were paid with money (or lands) for their service. More than a half of the commanding officers were representatives from the gentry. In times of peace, some of the regiments were usually disbanded.

In 1681, there were 33 regular regiments (61,000 men) and 25 dragoon and reiter regiments (29,000 men). In the late 17th century, regiments of the new type represented more than a half of the Russian Army and at the beginning of the 18th century were used for creating a regular army.