This study examined the effects of a 12 weeks detraining period on muscle strength and mass in older adults who had previously participated in a 12 weeks resistance training programme of high [80% of one repetition maximum (1-RM)] or moderate (60% of 1-RM) intensity. Twenty older adults (60-74 years), separated into a high (HI; n = 10; age: 65 +/- 5 years) and a moderate (MI; n = 10; age: 66 +/- 4 years) intensity resistance training group, were measured in the 1-RM knee extension and flexion strength, and the midthigh cross sectional areas (CSAs) of quadriceps, hamstrings and total thigh before and after a 12 weeks training period as well as after a 12 weeks detraining period. Maximum knee extension and flexion strength and the CSAs of all muscles decreased significantly (P<0.05) with detraining but remained higher (P<0.05) than pretraining levels for both groups. The HI group had a greater decrement (P<0.05) in maximum strength and the CSA of total thigh compared to the MI group but strength levels and the CSA following detraining were higher (P<0.05) for the HI group. The above data suggest that after a short detraining period of 12 weeks, muscle strength and hypertrophy levels of older adults decrease but remain greater than pretraining irrespective of training intensity. Greater declines in muscle strength are observed following HI training but still muscular strength and muscle mass are retained at a higher level than with MI probably due to the higher gains achieved during the training period.