Caffeine and the trace metals iron (Fe), copper (Cu), chromium (Cr), magnesium (Mg), calcium (Ca), zinc (Zn), lead (Pb), silver (Ag) and mercury (Hg) were determined in six locally purchased mineral water drinks in Ile-Ife, Nigeria in a bid to determine the constituents in the drinks which may be responsible for their observed in vitro spermiostatic actions. There was no association between the caffeine and the trace metals content of the drinks and their in vitro inhibition of sperm motility. Some other possible factors are also discussed.