This study examined the influence of familiarization with the backward, overhead medicine ball throw test of explosive power. Male rugby players (N = 28) aged 15 to 16 (M +/- SD = 15.1 +/- 0.5) years completed the medicine ball throw six times. Repeated measures ANOVA indicated that the distance thrown differed across trials (F5,135 = 12.83, p < 0.01). Least significant differences post hoc multiple comparisons revealed significant differences between a number of trials; however, no significant difference was evident between the fifth and sixth trials (Mdiff = .005, p > 0.05). Typical error of measurement became less as trials progressed, with the typical error of measurement being 0.10 m between the fifth and sixth trials indicating little within subject variation between medicine ball throws following a familiarization period. The backward, overhead medicine ball throw may be a practical, reliable method to assess total body, explosive power of male teen-aged rugby players; however, completion of at least 5 to 6 practice trials is suggested for participants to obtain a stable score.