The genus Pituophis (Serpentes: Colubridae) contains three species of snakes in the United States (Collins, 1997): Pituophis catenifer, Pituophis melanoleucus, and Pituophis ruthveni. The Louisiana pine snake, P. ruthveni, was elevated to specific status by Reichling (1995) and is endemic to western Louisiana and eastern Texas (Conant and Collins, 1991; Reichling, 1995; Thomas et al., 1976). Rodriguez-Robles and De JesusEscobar (2000) agreed with the recognition of specific status for P. ruthveni, but few data have been collected on the natural history of P. ruthveni since its original description (Stull, 1929). The paucity of data on P. ruthveni is because of the snake’s limited distribution (Reichling, 1995; Thomas et al., 1976), low population density (Jennings and Fritts, 1983; Reichling, 1989), and secretive nature (Reichling, 1988). A radiotelemetry study initiated in 1993 (Rudolph and Burgdorf, 1997; Rudolph at al., 1998) confirms the basic conclusions about the ecology of P. ruthveni obtained from collection records. Pituophis ruthveni is primarily associated with pine forests in sandy soils within the historic range of longleaf pine (Pinus palustris). Telemetry data indicate a preference for welldeveloped herbaceous vegetation generally maintained by fire (Rudolph and Burgdorf, 1997). A close association with Baird’s pocket gopher (Geomys breviceps) is evident at all sites (Rudolph and Burgdorf, 1997). As part of a rangewide natural history study on P. ruthveni in Louisiana and Texas, we studied 30 naturally occurring (one juvenile, 16 adult males, and 13 adult females) and eight captive-bred (seven juveniles and one adult male) pine snakes in the field for up to 43 months. The objective of this paper is to characterize the growth of this rare and poorly known species. We also compare growth rates of P. ruthveni with data from other studies of Pituophis. Because of the extreme rarity of P. ruthveni, animals (N 5 38) implanted with transmitters were located in several study areas: Bienville, Sabine, and Vernon Parishes in Louisiana, and in Angelina, Jasper, Newton, and Sabine Counties in Texas. All sites are within his-