The main contribution of this work is to propose efficient randomized leader election and initialization protocols for Packet Radio Networks (PRN, for short). As a result of the initialization protocol, the n stations of a PRN are assigned distinctintegerIDs from1 to n. The resultsinclude protocols to: (1) initialize the single-channel PRN with the collision detection (CD) capability in O(n) rounds with probability at least 1 0 1 2n ; (2) initialize the k-channel PRN with CD capability in O( n k ) rounds with probability at least 1 0 1 n , whenever k n 3 log n ; (3) elect a leader on the singlechannel PRN with no CD in O((log n)2 ) broadcast rounds with probability at least 1 0 1 n ; (4) initialize the singlechannel PRN with no CD in O(n) rounds with probability at least 10 1 2 pn ; (5) initialize the k-channel PRN with no CD in O( n k ) broadcast rounds with probability at least 1 0 1 n , whenever k n 4(log n)2 .