The purpose of this study was to determine the effects of a 12 month holistic exercise training programme on gastrocnemius tendon properties of elderly females and to compare their tendon properties with that of young females. We investigated the in-vivo mechanical tendon properties of 15 older women (OLD: age range 69-82 years) and 8 younger women (YOUNG: age range 23-30 years). From the OLD group, 14 volunteered to participate in a training programme and were randomly allocated into either a training (TRAIN; n=7) or control (CONT; n=7) group. The TRAIN group undertook a 12 month exercise programme (2 supervised 1 hour sessions and 1 home-based session per week) that consisted of resistance exercises (2-3 sets of 80-100% of 8 repetition maximum) as well as aerobics, walking, stretching and tai chi, whilst the CONT group maintained their normal daily activities. Graded maximal isometric contractions of the plantar flexors were carried out on an isokinetic dynamometer with tendon elongation recorded in real time using ultrasonography at the myotendinous junction of the gastrocnemius lateralis (GL) muscle. Tendon stiffness and Young’s Modulus (YM = stiffness x resting tendon length / tendon CSA) were calculated from elongation and force; with MRI used to determine tendon CSA and ankle joint moment arm. The study had local ethics committee approval. Differences between age groups were assessed using independent T-tests and repeated measures ANOVA were used to assess timexgroup interactions. The GL tendon stiffness at baseline in the OLD group was 60.1% (15.1 ± 1.7 v 25.1 ± 5.3 N.mm^-1; mean ± SEM; P<0.05) and the YM was 53.0% of that of the YOUNG group (P<0.01). Tendon stiffness increased 84% in the TRAIN group following the 12 month exercise programme from 16.1 ± 2.4 N.mm^-1 to 29.6 ± 4.3 N.mm^-1 (P=0.01). The observed increased stiffness in TRAIN resulted to a greater extent from less tendon elongation (44.6%) than greater force production (4.6%) post training. YM increased 86% in the TRAIN group following the training programme (P<0.01). The stiffness and YM of the GL tendon in the CONT group did not significantly change during this period. Carroll et al. (2008) recently observed no differences in patellar tendon stiffness with ageing. Site-specific differences and a greater loading due to increased body mass in their older group may explain the discrepancies. In conclusion, although the OLD had significantly lower tendon stiffness and YM prior to training than that of the YOUNG, the values between the TRAIN group and the YOUNG after the 12 month training programme were comparable. Thus showing that the age related decrease in tendon stiffness can be improved by an exercise programme that has shown holistic beneficial effects in elderly populations.