The cytokinin 6-benzylaminopurine (BAP) is a growth promoter that can delay leaf senescence. Therefore, the objective of this study was to study the effect of BAP on growth, senescence and in vitro degradation of Lolium perenne L. (var. Linn). The experimental design was completely randomized with 4 treatments: 3 concentration of BAP (T:0.1 mM; T2:0.01 mM; T3: 0.001 mM); and a control without BAP (T0). Plants were grown from seed at 25 kg/ha on 68 pots containing a mix of soil:agrolite:peat-moss (1:1:1), in a greenhouse. Plants of 8 mo were cut at 5 cm above substrate. At 21 d of regrowth, plants were sprayed weekly during 65 d (7 times). The variables evaluated were: leaf growth and senescence during 112 d; soluble proteins and photosynthetic pigments during 84 d; chemical and morphological composition and in vitro degradation of the cell wall (6, 12, 24 and 48 h). Means were compared using the Tukey test (P < 0.05). All BAP treatments increased net leaf growth (T1: 32%; T2: 18%; T3: 39%) with respect to the control, but leaf senescence and photosynthetic pigments were not significantly different (P > 0.05). BAP 0.1 mM promoted accumulation of leaf soluble protein (3.55 mg/gFW) and reduction of acid detergent fiber by 6%, as compared with the control. In vitro degradation was increased only with 0.001 mM BAP at 60 d of regrowth (T0:0.50; T1:0.43; T2: 0.52; T3:0.53). It may be concluded that BAP increased growth and leaf protein of Lolium perenne L. and reduced cell wall components.