The purpose of this study was to investigate the effects of shoulder isokinetic strength training on 50 M sprint time (50ST), propulsive force of arm stroke (ASP) and whole stroke (WSP) in front crawl swimming. Twenty-eight swimmers (8 male and 20 female, Age=18.3 ± 1.3 yrs, Ht. = 165.0± 8.8 cm, Wt.=57.8 ± 9.0 Kg) were matched and then randomly assigned to a isokinetic strength training group (IST, n=14) or control group(n=14). Both groups had the same swimming training program, except that the IST group added shoulder internal/external rotation isokinetic strength training using the MERAC dynamometer. All subjects trained six times per week for five weeks. Statistical analysis indicated that there were significant(p<0.05) changes in the IST group: dominant arm internal rotation strength at speed of 180 deg/s (from 26.3 ± 9.1 ft-lb to 33.8 ± 9.2 ft-lb), 50ST (from 37.1 ± 4.8 sec to 33.4 ± 4.0 sec), ASP (from 2.2 ± 1.7 Kg.M/sec to 2.5 ± 1.9 Kg.M/sec) and WSP (from 3.4± 2.4 Kg.M/sec to 3.6 ± 2.4 Kg.m/sec). No significant(p>0.05) changes were found in the control group. It is concluded that 5 weeks of swimming training combined with isokinetic strength training could significantly improve swimmers' propulsive forces and swimming speed.